DarrkPhoenix: Something you need to understand is that it simply isn't worth having a discussion with some people. Ideologues, sophists, zealots, etc- there's nothing worthwhile that can come out of a discussion with such people.
That's the OP in this case. The problem is, you can't win an argument that's wrong. How do you prove that DRM is dangerous to the industry when DRM has been part of the industry since games were sold? (Granted it was called "copy protection" then.) As another example consoles are DRM laden, and they're doing very well. So are mobile games. Your argument is irrational in the first place, so you can't win it.
It's possible to argue that DRM doesn't really help and is a waste of time and money, it's possible to argue that it removes consumer rights and hurts legitimate buyers, it's even possible to argue that it hurts sale, but if you're taking the "ruining the games industry" line then you will lose every time, because you'll always be branded the clueless zealot.
If you want a lengthy and well thought out series of articles by a respectable author that hits copyright and DRM in the head, check out
Eric Flint's Salvos Against Big Brother. Read it or let the person you argue with read it.