Get rid of self-voting entirely.
You can't. It is obvious that grumpycat and checkthisout are the same person. S/he can as many accounts as s/he wants (which brings up the other question of what is the reason to have a delay of over a week for registration?!?).
When you create a perverse incentive, you have to figure how to negate it. I've been thinking about this issue and can't figure out a work around. No self-votes? Nope. Cap on how %age of rewards pool any account can get in a day or lifetime? Nope. Limits on comment rewards? Nope. Actually, that could work. Buuuut it would result in them to creating more garbage posts instead of garbage comments which don't show up in /created. #ugh