I'm curious why you think folks at gumroad don't "work much" and that most of the work had been done by those no longer at the company. Did you used to work there and have some insider knowledge?

Seems to me the post wasn't even claiming to have >$1M ARR either (there was a graph for the creators ARR which I think is different?) and that everyone does work... they just do it using a non-traditional process.

edit: There's this: https://news.ycombinator.com/item?id=25675713 which might point to >$1M ARR?

edit 2: I also realized in a business like this ARR just doesn't matter (who cares? You're not trying to raise another round or IPO). https://twitter.com/shl/status/1215673023472140289 shows the net profit and it amounts to 1 senior engineer's salary. That's amazing for a small business with a small number of employees but it's not exactly living high off the hog.