But he literally made a real game and released it. It was a long process for sure, but you can’t say it’s infeasible.
He had previously built and sold two games, each of which made him millions, funding the next effort. Not infeasible, but building on repeat success.
I don’t see why this weakens the example. He has repeatedly built and released games from his own engines and now language/compiler. Money was increasingly required but he had made that money through the same process.
I don't think you can say that making wildly successful games one after the other is "feasible" for anyone who's interested in making games.