As soon as you can prove that collection of 20k doesn't exist, without a doubt, I'll get behind this idea of banning someone for making that claim.. With the people who claim to own a game before it is out, well, that's obviously a way of saying "hey, I pre ordered" and instead of banning people for that if it were a real problem it could just be set up so people can't say they own a game until it is released.
I'm curious, though. If you got your way, would you then start trying to ban people who haven't posted their full collection. I mean, that would be a lie too, right? God, I better get unlazy and fill that collection of mine out before you go screaming to have me banned too!