I have a funny story very related to this.
In the 90s i was living in SF. One night i was waiting at a muni stop and i look to my left and there is Stu Hamm with a gigbag over his shoulder (it was an urge bass!)
He had just played a gig and was heading home, on the bus, to his rented apartment (we got to chatting and i asked where he was going). He alluded to the fact that he made very little money doing what he was doing. I know it is odd that we had a conversation like that in the middle of the night out of nowhere, but it was like he was telling me it's not all it's cracked up to be.
I swear he even hinted it wasnt worth it and was thinking of getting out of it. He just seemed tired and fed up.
Now this was before the internet, so I'd assume there are many more options to make money nowadays, but i came away with the feeling he was making like 70K a year bejng one of the world's greatest bassists
Absolutely 100% true story.
Anyway, takeaway is i dont think he ever made much money. Certainly not millions.