Of course, to be a
superhero, one simply needs to have some sort of
congenital or otherwise
involuntary power or thing that makes you different, and then decide to
run about in tights stopping
evil. On the other hand, becoming a
supervillain requires huge amounts of
resources if you don't want to just be known as So-and-so the
Super Mugger. Thus, there is definitely a
selection effect at work here on the supervillain side! While you can become a
hero or
villain without
powers, it's easy to be a
superhero if you have powers but still hard to be a
supervillain worth chasing. Also, a number of supervillains seem to have been created when the villain him or herself was engaged in some
scientific inquiry gone
hideously wrong.
One minor nitpick on the original node: Iron Man. Tony Stark was definitely overeducated; he became Iron Man because while being held captive by the enemy (DerekL reminds me it's the Vietnamese, often referred to in the stories as Asian Communists!) he was made to build a superweapon; knowing that the shrapnel in his chest would kill him if he didn't do something, he created the Iron Man armor as a dual supersuit and life-support system...all while being held in some crappy underground hideaway.
Nitpick 2: kenata, Robin (in at least one incarnation) was actually a college student when not dashing about in tights...not overeducated, but too young to be one or the other, and on track for overeducation...