Music hasn't really changed me. It's helped me express things I haven't been able to do otherwise. My most emotional songs have been composed in critical stages of my life. It's a nice outlet I guess.
I'm not in it for the money or the fame, but they're bonuses that may come with it and I wouldn't turn them down if they ever did. I'm passionate about what I do because I like what I do, I enjoy it a lot.
To me, the best thing about making music is seeing peoples' reactions to it (assuming you've reached a point where you can actually get reactions from people with it). It's great to know someone out there probably downloaded your song and plays it before they go to sleep, or to know that it helped someone in a rough situation.
My music is actually rather personal to me. I've only shown it to a handful of IRL friends.