Originally Posted by EvilLlama
"To me, true music is the expression of emotion and feeling through sound and such."
Not that I like him (I'm more of a Nightwish fan), but Soulja Boy fits your definition. Direct quote from Wikipedia: "In September 2007, his single "Crank That (Soulja Boy)" reached number one on the Billboard Hot 100. The single was initially self-published on the Internet, and it became a number-one hit in the United States for seven non-consecutive weeks starting in September 2007. "
So he's been doing his stuff long before money got into play. And from the lyrics of songs like "Successful", I can say his work is personal to him and has emotion. Sadly, I lack the musical knowledge/terminology to really help come up with a better definition, but your original definition of "true music" is definitely vague.
After reading the lyrics to "Crank That", I've never felt more wrong in my life....
"Watch me crank dat, watch me oh...
Watch me crank that Soulja Boy"
The symbolism behind these lyrics obviously means that something inside of him is devastated and he needs to crank it out.
"I'm bouncin' on my toe, watch me supersoak dat oh, I'mma pass it to Arab, and he's going to crank it fo' sho'."
This obviously means that he wants to supersoak something and is being friendly, by passing it on to either a guy named Arab or some Arabic guy so he can crank his pain or something... Soulja Boy has no expression within the instruments though, so obviously his lyrics are saying alot