Perhaps the BEST B1G Forum anywhere, here at College Football Fan Site, CFB51!!!

Having spent a lot of time in SJ/SF, I agree that it's quite useful there. SF is so expensive that it's nearly impossible to live in the city unless you're rich, and it's so space-constrained that it's almost impossible to justify a car day-to-day. And because it's so centralized, having BART to get right into the heart of downtown is nice--particularly because BART goes to SFO. For people coming into the city that know they won't need a rental car, BART gets them from the airport to downtown in ~25 minutes IIRC.
Light rail in San Jose and on the Peninsula? Much less useful. Outside of SF, there's a lot more sprawl, where it's unlikely that you not only live close enough to a light rail station and your destination is close enough to a light rail station to justify the additional time and cost of taking light rail. For travelers, if you're there on business, there's no connection from SJC to light rail, so if you wanted to get to a light rail station you'd need to Uber/taxi to the light rail. At which point you might as well either rent a car or just Uber from destination to destination.
Question: what brings you to downtown LA, and do you think your experience is typical? If you live close to SFO, it should be no more than a 2 1/2 hour trip to get you to LAX. It's the getting from LAX to downtown LA that's the hard part.
I will highlight that if you're trying to get to downtown LA from LAX, it's terrible. Unlike SFO to downtown SF, there is NO mass transit connecting the two. I think that would be an excellent use of mass transit, but right now you have to take a bus from LAX to the Green Line, tranfer to the Blue Line, and then transfer to the Red Line if you want to get to Union Station. That would be a pain in the ass, and take at least an hour plus.
But I can't imagine why anyone needs to get to downtown LA?
Part of it for me is living in Orange County and absolutely hating to drive into downtown LA, but outside of sporting events, concerts, etc, I can't imagine many reasons to go to downtown LA. And HSR would take you to Union Station. LA also has so much sprawl that you'd find yourself having difficult public transit here anyway, or taking Ubers/taxis everywhere.
Generally business travelers are going to need the freedom of a rental car and can shoulder or expense the cost, and probably aren't going straight to downtown LA anyway because business in LA is all over the place. Which means that getting to LAX (or Burbank, or Ontario, or Long Beach, or John Wayne--we do have 5 major airports here) is probably just as functional as getting to Union Station downtown. If it's about vacationers, I highly doubt that enough vacationers are going to be riding HSR to create enough ridership to make any sense.

Lots of stuff to unpack here. Most of my work in LA has been downtown. While Burbank can be a better airport to fly in and out of, there are far fewer flights in and out of there (same for Long Beach and Orange County), so LAX is the most common for me. And I can't remember renting a car in LA. Too much hassle driving--the traffic is terrible and the parking is expensive. Last time I was down there was for pleasure with SFIrish and the boy. We flew into Long Beach (left the house about 7 am, took a cab to the airport--about 7 minutes--waited for the flight, and arrived in Long Beach at 11:15, I think, so four hours to get to the airport) and took a ride service where we were going. The second trip was to Orange County, so cost a bit more, but it was still far less expensive to pay for the ride share than to rent a car. The fare was no less than an HSR fare would have been, the time it took was at least as long, and the experience was much less pleasant. Great use for HSR. With a stop at either Union Station or Anaheim, that covers a lot of
As for travel time from SFO to LAX, you can get it down to about 2-1/2 hours (without routinely missing flights) if you are willing to take a little risk in how much time you sit in the airport--I'm cautious, so I allow more time. The flight time itself is negligible, but security and the vagaries of air travel add time on average. A lot of time. And then, yes, it's getting into and out of LAX that adds a lot more.
The other issue is population and jobs growth. SFO is basically at capacity now, and San Jose and Oakland are near it. To get more people connected to SoCal will require another way to do it.
I think the only light rail in the Bay Area is down in Santa Clara (e.g., San Jose up to Mountain View, I think). Most rail here is heavy (BART is electric, but still heavy rail). I live on the Peninsula and the traditional diesel electric train is the best way to get into my job in San Francisco, though the southernmost BART station is also convenient for me and I use it a bit, too. The traditional commute train has very strong ridership up and down the Peninsula during commute hours, as does BART--and that's with generally weak first mile/last mile transportation options when you get where you are going. Population density and growth is such that everywhere on the Peninsula and in the Silicon Valley, the traffic (and cost of housing) is bad. Commuting intercity in a car sucks most of the time. The current plan on the passenger rail is to convert to electric rolling stock--construction is underway and I think is scheduled to complete in 2022. Electric rail will increase the speed and frequency of the trains, making them even more useful.

You are right about light rails failure to connect to SJC. Ridiculous. Other than that, I'm not real familiar with light rail in San Jose, as I'm not down there enough to make use (or not) of it.

Yup--a lawyer, so most of my time down there is going to downtown law offices and the courts (Stanley Mosk, which is the main courthouse, most of all).

My experience on rail versus planes is that 3 hours on rail is way better time than 3 hours getting somewhere by plane. No more than about 15 minutes idle time (on the platform), then all the time on the car itself you can work, nap, read, whatever. That NorCal/SoCal flight, with only about 45 minutes in the air, there is precious little time that can be productive; most of it is security, gate time, then takeoff and landing time--with very little space to use a computer, even when I can. So I would take a three-hour train ride over a 3-hour flying experience every time.

Now--as to the bureaucracy and resulting expense of the California HSR project, that's a whole different question. Of course, a significant portion of that cost has been driven by all the challenges to the rail thrown up by anti-rail people who knew that their best bet to kill it was to make it more expensive.

One last thing, fwiw--my house is seven houses and one two-lane road away from where the HSR track would be (where the commuter rail is) in my neck of the woods.

I once was scheduled to fly to London out of Dayton (to save money) through Atlanta.  When I got to Dayton, I was told all the flights to ATL were cancelled.  The agent got me on the flight from Cincy to London direct though, I just had about 60 miles to drive in about 60 minutes.  I made it, barely, there was no one in line in Cincy at the Delta counter.  I got on the plane and realized all my travel plans were based on arriving at Heathrow, and this plane was going to Gatwick  No internet back then.

Last March, when the wife and I were headed to Italy/France for our elopement and honeymoon, we were originally supposed to leave from LAX on Wednesday morning, through Philly, then direct to Rome. We were supposed to arrive first thing in the morning Thursday and have all day there, and then Friday had reservations for the Vatican. 

Well, this was when the big Nor'easter hit last spring, and lo and behold I find out on Tuesday that the Philly->Rome flight is cancelled. So I spend hours on the phone with American, with a nice lady who is *trying* to be helpful but has her hands somewhat tied because we were flying on points instead of an actual revenue fare. Everything she's finding has us leaving on Friday or even Saturday, which basically means we have zero time to do anything in Rome before moving on to the Cinque Terre. 
So I'm working every angle I can work, and she's looking up everything she can find. Eventually she says "hang on, let me check something with my manager." Comes back and says she's normally not supposed to do it, but if I was willing to not only change planes but change airports in London, she could make it work and I'd leave Wednesday evening. I say "sure". 
So we fly direct from LAX to Heathrow, arriving about 9 AM. We have a 6 PM flight from Gatwick to Rome. I have coworkers in an office in Leatherhead right near Gatwick, so I'm trying to guilt them into hanging out and showing us around and maybe having pints [my treat], but given that it was going to be the middle of a work day, no luck. I start researching how to make use of those 9 hours and maybe see some of London instead. Figure it might work, although shlepping our bags around London all day didn't sound fun.
As it stands, we get in at 9 AM, we're just dead tired from the redeye flight, not feeling well from fatigue. Sightseeing wasn't an option. We eat crappy airport food in Heathrow, catch an Uber to Gatwick, only to realize it's about noon and they won't let you check in for a flight or past security until 3 PM. So we sit on terrible chairs in baggage claim, me reading my kindle with my legs up on my suitcase and her feeling like hell trying to sleep, until 3. Finally get through check-in, through security, and we're into the terminal. The sad, sad terminal. We manage to choke down some fish & chips and my wife looks at "mushy peas" with disgust [she doesn't like peas anyway] and a couple of pints, and finally get into Rome about 1 AM Friday morning. Crash and just barely wake up in enough time to get to the Vatican. 
To this day, I'm not sure if my wife can remember the name of Gatwick. For now and forever more, it's just going to be "sad airport" in London lol!

I think it was beneficial for me to finance the 2015 Chevy Silverado for 5 years and wait until one year had gone by, then pay it off

can't we simply get jet packs for everyone?

Contrary to popular belief, the US's rail infrastructure by and large is pretty damn good at what it's meant to do... move freight. The fact we can't just put bullet trains on tracks full of freight trains doesn't mean we have "poor" rail infrastructure. 

If the US wants a nationwide high speed rail system then a whole new network of tracks will need to be built and it should go without saying that is extremely expensive. 

But really, high speed rail is only feasible in areas of very high population density, which most of the US is not.