Most 17 year olds in my experience have no idea what they "want to do", and it stressed them because they surmise they are unusual. Everyone else is going to college, except for the real dummies, so they go to college also figuring they will figure it out in college, and it seems like fun, and you might meet the dream of your life.
We've all seen "professional students" who never get past this, they often change majors on a whim and just keep going.
I recall in our high school, there were 4 or 5 "levels" of classes one could take. The top level was IB, and just below that was AP, and below that was "College Prep". I think they had some fancy name for whatever was below that also, but I forget what it was. Plenty of kids took CP level course and went to college somewhere, usually not one of the better options around.
"We" are herd/social animals with a strong urge to "do what everyone else is doing".
The hardest thing in life to be is yourself.