I'm don't know much about protection of games but I know studios invested a lot of money for protection, still it gets hacked/cracked + lot of protections do more harm than good - Ubisoft and their Assassin's Creed's protection or StarForce protection.
I myself had problem with StarForce, couldn't run PC with it once (I own legal copy of FlatOut 2), I had to delete it and crack the game iirc.
On the other hand, I once read about Ironclad Games' Sins of Solar Empire, I think Stardock Entertainment published it w/o protection and still they made money from it.