How so? Data point: I don't pirate music, partly because I'm paranoid about getting sued by the RIAA. I'm sure I'm not the only one.
frequently-pirated music makes more money than less-pirated music.
Yes, popular music makes more money than unpopular music. Duh.
pirates spend more money on music than non-pirates
Which, even if true, is not a demonstration of "pirates spend more money on music than they would if they weren't pirates".
I am extremely skeptical of the idea that piracy helps the music industry. It smells strongly of the kind of thing that people believe in order to justify their own actions, rather than the kind of thing that people believe because it's likely to be true.
If you're still pirating music in 2010, and the track you're pirating is available on the Apple Store for 99 cents, then you're just being a cheap bastard.