1.) Would it change me?
Unfortunately I think yes. Most of the things I could want really aren't that expensive. My dream car is in the five figure range. $15 buys me the most fun in the form of a World of Warcraft subscription. However knowing my impulsive personality, I'm sure I would get into trouble buying overpriced stuff, end up consuming too much time managing stuff, and boost my already existing anxiety.
2.) What if someone gave me $100m out of the blue?
I'd honestly try to find a way out of it. At $100m someone would be trying to scapegoat and frame you for whatever their illegit purposes are. You don't want to go to jail do you? Even at much lower thresholds its too suspicious. Indirectly knew someone that got burned for accepting $50k (to say they didn't see nothing and it didn't turn out well for them).
In the spirit of the question ruling out the real risk though, I'd probably end up buying some nice stuff and quit my day job but also certainly join the Warren Buffett pledge to give away at least 1/2 of my wealth to good causes even if I didn't get recognition. I believe I would be happiest knowing that my efforts in the world help others. I already enjoy this philosophy now but on a much smaller scale as I donate time and money to causes I believe in.