My two biggest regrets in my education are (1) taking the 'college prep' classes in high-school instead of the welding and small engine repair style classes and (2) majoring in CS instead of minoring while studying a field like biology or chemistry that's full of things that need programs written about them (and looking down on the kids who did, because I was the superior math/CS student).

I mean, I don't think I have a bad life, but it's kind of a regret that when I sit down and think about things to program for fun, I think about theorem provers and compilers, which there are already bunches of.