As I'm sure I've said before, I'm married to a politician. A local one, but one who will seek higher office. She isn't paid beyond a tiny stipend, so what she does is essentially volunteer work. Her next campaign will be for a paid position, but it isn't a lot of money, no matter what elected office you win. Most people who go into politics are wealthy already. We are comfortable, certainly, but not wealthy enough to own a second/vacation home, a boat, or any such thing. Like most, we worry about how we will pay for college, but unlike most, we are relatively certain we can pull it off without our children going into debt. Becoming and staying a politician is much easier for people who are independently wealthy, so--unsurprisingly--most people who are politicians are independently wealthy.
Sitting on the sidelines while constituents savage your spouse because she made a decision they disagree with is fascinating (and difficult). Anytime an elected official takes a stand that is unpopular with more than about 10% of the voters, the outpouring of negativity is stunning (and it can be even when it's just a handful of people who disagree). And that is at a local level, where these constituents are literally our neighbors. If they want to, they can knock on our door, and many of them have my wife's personal phone number. Nonetheless, rather than talk to her, they savage her on whatever platform they have, calling her all kinds of things, and implying that she is bought by some interest or another. And she is very popular in this town. It isn't for the feint of heart.
As with any person, the politician approaches any issue with preconceived notions. Some people--and some politicians--are better than others at challenging their own preconceived notions. And in a democracy, these elected officials have to work with other elected officials to get things done. And they each have their own set of preconceived notions that impact what they expect in a given situation. They also can't be experts in every issue they need to consider, so must seek out experts to learn more and often for guidance. And, they are making, and amending laws that have be generally applicable to an amazingly broad array of issues (so the idea of a simple bill, while appealing, is generally naive).
Even the money in politics isn't as simple as we would all like. Again, we are relatively comfortable, but to win a local election, where there is no real pay, takes a significant chunk of change--more than we, in our reasonably comfortable life--could easily part with. So the politician raises money through donations. Determining who to take donations from, and who not to, is itself fraught in a business where not pissing people off is relatively important. Some people think public funding is the answer, but then how do you determine who gets the funding? What's the cutoff? Additionally, one indication of whether someone is capable of rallying people behind them (an important quality for a representative of the people) is whether they can effectively raise funds. Receiving money from a donor doesn't make the politician beholden to the donor, but of course donors tend to favor candidates they think will agree with them most of the time.
Term limits have already been adequately dealt with above, but I'll simply add that in California we have them, and they haven't had the desired effect (though there is something to be said for turnover; there is also something to be said for experience and relationships). Ranked-choice voting occurs in San Francisco. It's been there for a few elections now. It's still--I think--in the experimental stage. Maybe it helps.
The federal government, even more than state and local governments, is a very big ship that manages a massive number of incredibly complex tasks. Simplicity is rarely going to function well at the federal level. In the United States we have always tended towards less government intervention than occurs elsewhere, but we still need a functional government. No matter the size of the government, people always think it costs too much because no one likes paying taxes, and everyone can always find some government program they disagree with, which plainly (to that taxpayer, anyway) wastes their money. But, for anyone who has ever compared charity-led intervention with tax-funded intervention, it is obvious that private action has a very difficult time mimicking government action.
Despite our relatively limited government intervention, we always (and have from the beginning) argue about how much and where to intervene. That is a healthy part of democracy.
People also really like the concept of experts in a field making decisions relating to those fields, but constituents hate decisions that are made without their input, even if they don't have a clue what they are talking about. That is actually a key role for the politician: to act as the conduit between constituents (and their under-informed feelings) and experts, who sometimes lose sight of the impact their decisions might have on the common person.
At this point, I'm just rambling, but as I've had a front row seat to this whole politician thing, it has become very clear how much more complicated it is than the average person wishes it were. There are, of course, bad apples who are politicians (as everywhere else in life), but we would all be well served to remember each other's humanity--even the politician's.