Power
You have a huge and important role in the lives of the band members themselves. They depend on you to negotiate contracts and book gigs in their interests. You're their only representative in a world they probably wouldn't be able to navigate very well without your help.
The role you have in the music business industry on the whole is a little harder to discern. If the band is well-respected in the music world, people are going to listen to what you have to say. But if you're managing a band of nobodies, it's going to be really hard to get a club owner to even return your phone call.