there should be an app like Uber but just for sharing games
just kidding, that would end up a disaster
As cool as game sharing sounds, I don't think trusting random people online with your stuff is a good idea.
Think of it like this, Chad borrows your Crash Bandicoot 3 disk during grade 5, keeps making up excuses to keep it longer, as the years go by eventually you matriculate, you then realise that he probably still has it, using your CSI skills to track him on Facebook and says that he gave it back to you. Goddammit Chad, no you didn't.
Edit: d'oh! you meant PSN account sharing. I guess if you're careful, it should be fine