Let's do some maths! There are 5 people in my band, we'd like to earn £20,000 each a year (I think that's a fair amount), £20,000 x 5 = £100,000 a year the band needs to make through sales and playing gigs. Now management will take let's say 15% to 20% of that so let's say ideally we want to earn £120,000 - that's a lot of money!
The answer, I believe, lies in hard work and creativity. One of my favourite bands Vulfpeck really hit the mark in this field - on top of their stellar musicianship they've taken the world by storm with their viral videos and crazy streaming stunts. Have a read of this to see how they made $20,000 on Spotify: https://www.theguardian.com/music/2014/jul/25/vulpeck-the-band-who-made-20000-from-their-silent-spotify-album