Not with many people. Every ISO I have is a game I own (not even rented) that I dumped personally on my own PSP. Yes, there is quite a bit of piracy on the PSP, but it's not any worse than any other platform, and better than some.
Ditto for my PSX EBOOTs - every one of them was dumped from my own discs using my own python script I wrote back when a bunch of us were still working out how to get CDDA in PSX games in popstation.
I take decent care of my discs, but I've still got a few (PSX mostly) that aren't readable anymore. No matter how good the media, it'll eventually go bad... or the drive will. Having an electronic copy of my games means I don't have to worry about either. And playing legal backups instead of the original UMD means my UMD drive will last that much longer due to lowered wear-and-tear.