If someone cheat and get more money on on quick blocks, than someone must lose on quick blocks. I am surely will not be the looser (nor will my customers).
You don't lose on quick blocks. You lose on slow blocks. People who "cheat" simply lose less than you on slow blocks.
If you want to check whether people are "cheating", don't look at quick blocks. Chart computing power against time, and if people cheat, you'll notice a drop as blocks grow longer.