What I see repeatedly among those who have become famous is that, rather than them changing people's lives through music, they themselves have been changed (and not in a good way) by the "celebrity machine." Look at Miley Cyrus or Lindsy Lohan, for instance. As for people being changed through the music of any given individual - there will always be a new idol. Back in the day it was Elvis Presly and the Beatles. Now the names are different, but the dynamics are the same.
If you love the Lord and He has gifted you with musical talent, you should certainly use that gift for His Glory. But, dedicate that gift to Him and seek to please Him alone in your use of that gift. Let God take care of how well-known you become or how big your audience. People whose hearts are prepared as good soil will respond to your music. People whose hearts are dedicated to their own lusts will happily make you the object of their idolatry whether that was your intent or not. They will gladly heap garlands of flowers upon you, make offerings to you, put you on a pedestal, and make their rooms into shrines to you. Of course, they will just as happily toss you out for whatever new idol tickles their fancy.
I have to go to work, now, but I want to continue my thought tomorrow because I don't want to leave things on what may seem somewhat of a harsh note, so please bear with me.