Stardew Valley is in the top 5 selling indie games of all time, with 50 million units sold. It's owned and run entirely by one person (the donor in OP's link) - he ended his relationship with a (small) games publisher a few years ago, and runs everything himself.
Additionally there is a concert series that's quite good and other merchandise.
My girlfriend owns the board game, she enjoys it!
Does this mean he does the mobile games himself now? I remember he had outsourced those for a while.
Think of it this way; he subcontracts, but he deals with the subcontractors himself.