Most of the musicians I know make the bulk of their music-related income from private tutoring, its what funds the rest of it. They usually also will have a day job of some sort.

Recording and producing music, making music videos, etc is a massive cost center that may or may not break even. Usually not.

Playing live gigs is usually a money loser for most - venues often have extremely unfavourable terms (especially when starting out - a lot of places are pay to play, where you have to market and sell the tickets and at best get to keep what's left over after venue hire is covered).

The real money is basically in teaching the offspring of upper middle class people how to play an instrument.