The real cheaters don't have much to lose actually.

They sell items on Ebay, even if you ban their keys they will have leftover cash to get a new one. Banning several of their accounts won't do them much harm.

I started to support Blizzard since Warcraft 1. I bought War 1, War 2, Diablo 1, Diablo: Hellfire, Diablo2, Diablo 2: LoD, Starcraft, Starcraft: Broodwar, War 3. They ban my accounts for no particular reason, but i'd still support them, as in buying their future products.