not sure how familiar any of you are with biology, but genetics can kindof lead you toward the answer also, but not so precisely. Without going into great detail, in a small population, randomness causes everyone's genes to be the same after a while. Every allele (different gene, aka brown hair = one allele, black hair = one allele, etc.) will either be 100% or 0%. So basically, you're going basically broke or having a fortune most of the time, unless you're betting tiny. This doesn't explain the betting less than your edge idea, but i thought it might be interesting to some of you.