If you're a musician and you have enough fans, they'll start creating more fans as they tell people about it, large numbers of people will be going to your shows and other people will hear about you, you get on the radio, you get listed as "trending" on Spotify, etc. There's also nothing to slow it down, since once you record a song once, people can listen to it effectively infinitely more times without you having to do anything else.
To put it another way, let's say you have two randomly selected authors. Their average earnings are $1,000,000 per year. Is it more likely that they each earn roughly $1,000,000 per year, or that one earns $1,000,000+ and the other almost nothing?
On the other hand, you have two women whose average height is 1.7m. Is it more likely that one woman is 30cm tall and the other is over 3m tall or that they are both roughly 1.7m?