What`s the problem to find people who use BTC and make tournament among them? You can make fair games only when you can see your opponent`s "eyes". End of story
P.S. Chess isn`t about money at all.
Any kind of internet competition even if you can see your opponent in a webcam can be easily rigged, he could have second monitor in front of him or someone who will tip him the movies.
There is no way that you can play chess over internet for money while being sure that people are being honest.
P.S. So winners of live Chess tournaments are not rewarded with any kind of prize?