This is what I'm trying to do since 2017 [1], except the earning are merely 5k a month.
From what I can see around me, the rate of oss dev who make a living out of their project is similar to amateur / pro football player, with the big star everyone talk about, namely redhat & gitlab. I only know personally 1 other oss dev who is doing better but still way under what you get working for someone else
If you're doing oss and managed to get things to work, please reach out to me, I'd love to talk to you.