And you are perfectly right!
PICO-8 is one of the product that Lexaloffle do sell and they are the main money input for the owner. Yes it is a one man company.
He have a second source of income from his Pico pico cafe ( https://picopicocafe.com/index_en.html ), but I don’t think it is as high as software sales, and with the pandemic, not sure how much income he get from it.
As for making game, well, have fun, try things, can’t wait to see what you will do with it! Have fun!