Those folks usually have never asked themselves the question on a deeper level. A musician who is really out to make the world a better place through his music and can articulate his vision is going to succeed against a musician who plays an instrument slightly better.

A lot of people spend to little time into actually exploring their dream. That means that they can't draw as much motivation from it and they can't convince other people to support them in their dream.

You can go into the music business trying to play a zero sum game where you work hard to be slightly better than the competition. You could also go to communicate certain cultural values that you find lacking in todays music. Then you aren't playing a zero sum game and you also aren't in direct competition with a lot of people who just try to work hard to be a little bit better.