Yeah, but the musician's didn't publish their music on MP3, they did it on CDs, CDs that were used to make the MP3s from.
Musicians don't just want exposure, they do want money for their work. Yes, there are a lot of overpaid musicians out there, but it's not like they have job security. And playing out for little money really gets to you.
And this thing about them 'not getting rich too quickly', that's what the entertainment industry is. We worhsip our entertainers and give them lots of our money. And what's with this whole thing about 'then they get addicted to heroin'. The three artist you listed that you said inspired you to play guitar are/were avid drug users also. Hell, Jimi Hendrix died of a drug overdose.
People can be inspired to become musicians if they pay for music also. What, is there a new philosophy out there 'I've been inspired by your music, but it's not worth any money, you should just starve to death for all your hard work'?
And on another note, all those musician's you listed that inspired you to play guitar, their CDs can be bought easily enough.