It's not a lost sale if I never would have bought it at a retail price in the first place. Nowadays I tend to only buy games when they have insane deals on steam. Used to buy used PC games, but now I can barely find a new box in a store, let alone a used copy.
See, when you buy games at "insane deals" on Steam, the manufacturer is still getting some money - probably more then what they would get from a 2nd hand store selling the used game. Plus, you still get all the fancy features like online play.
In this way, selling a game for insane deals on Steam is not a lost sale for the manufacturer, but rather better economies of supply and demand. It doesn't cost anything (or very, very little) for Steam to maintain a given game on their service since they are a distribution network first and foremost. They don't have to worry about making sure there's shelf space for the Next Big Thing, whereas retail stores need to worry about that constantly. I can't tell you the number of games I've bought on Steam at insane deal prices that I likely would never have bought otherwise - certainly not in a store, where it was used, the disc could be scratched, etc (which I have had happen).
Do I necessarily agree with the idea that I don't really own my games (if we assume that EULAs are valid)? No, of course not. Has it become commonplace for every single software developer to make that particular claim? Yes. Do I care enough to make a fuss? No. If they started to take away my Steam games, then I'd have a problem.