[archmagi]

OK; here is what I think:
You know one of the basic rules of economy: for bigger gains you need to take bigger risks.
The fact is, geniuses think too much and in too much detail. they calculate risks too well.
a highschool drop out wouldn't do that (at least not as much as a genius or a Phd).
The second fact is that, the higher the educational level of people, the less risks they take.
Just to give you an example, they never prefer ppl with Masters or Phd degrees for Trading and stock exchange jobs. Why? because they are too risk averse.

Now your second question: How would geniuses do in Poker?
I think they would easily be very good 10-handed Limit Holdem players.
Put them in short-handed and/or No Limit situations and they will be eaten alive.