I think that success depends on a lot of factors. Success in math class means you can do the problems expected of you at the level being tested (obviously, some people go beyond that). Success in college (at a minimum) means graduating. Later, success probably means getting and doing well at it or making a contribution in some other way. For my cat, success means stealing my other cat's food.
Understanding subjects like math and English requires brain power. The higher you go, the more brain power you need succeed. Obviously, hard work is essential, but I think brain power is an entry requirement. I speculate that most humans probably have enough brain power to master arithmetic if they work at it, and that most humans
don't have enough brain power to master tensor calculus, regardless of effort.
The US school system refuses to recognize this fact. So (IMO) it defines "success" as "going to college" and pushes everyone in that direction --- even if only 12% of a graduating class is proficient at 12th grade subject matter. I like the idea of raising expectations, but I don't like the idea of misleading young people by telling them that going to college is the only way to succeed in life. I don't get that at all, actually.
If you have Down's syndrome, success may be holding a basic job. If you have amazing manual dexterity, being a top-notch car mechanic or lab technician or surgeon could be success. If you're great with kids, success could be running a day care business where the children thrive. Etc. For me, success is about pushing your own boundaries, doing something positive, and finding satisfaction (and hopefully happiness). (YMMV)
