Singing is definitely not a lucrative business. I've seen estimates on "Musician" on job occupation specialty websites, the kinds that help you decide careers and whatever, they estimate an average of 30-40k a year.
But it depends on a LOT.
Talent plays a big role. Image, connections, charisma, timing, and lots and lots of luck are required to make it big.
What kind of music do you sing?
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Educators destroy your brain,
but you don't know, so why care?
Fagotto