256 players get drafted every year. There are 124 DI football teams with a max of 85 scholarships per year. If every player made it to their senior year, and the draft only took seniors, and every class was the same size, a player would have < 10% chance of getting drafted. That's a lot of "ifs" just make it to the pro level, and that does NOT get you paid!
That says nothing of the odds of actually making a roster in year one, and says even less of sticking around the league long enough for those big paydays to set you up after retirement.
Basically, if you're playing the odds, the expected value of a college football scholarship isn't bolstered much by the professional payday. Nearly all the value is in that college degree (paid for by scholarship). So graduating with a degree that you can turn into a career is the best play BY FAR.
That takes us to graduation rates. These seem to be fudged a bit since, well, it's in the programs' interests to hide poor performance. You can do your own digging. Lots of articles about this, and it's not terribly great. The NCAA has their bookeeping, the football programs have theirs, and most expert agree that neither counts accurately. Best case, graduation rates are in line with general student graduation rates. Worst case, not even close.