If anything, the rewards for siding with evil should be greater, at least at the beginning. Most Evil people don't do evil deeds for the pleasure they get from murdering/stealing/etc, but instead because they are selfish, and doing those deeds benefit them more.
There's the common trope that doing Good will not be that rewarding in the beginning, but will eventually put you in a very good place. Evil, however, is rewarding up-front, but you'll eventually get what's coming to you.
