I think making these type of games simply becomes an unviable source of income in the current era.

I'm sure there's a named concept for this: the idea of the game is its selling point, and has to be revealed to consumers to market itself. But the market has low friction (via Steam distribution, and by copies being cheap to make w/ LLMs), so you can't reliably establish your product before masses take over, especially if you don't have reputation built up from previous games.

You have to be bringing in something else for this not to happen, trade secrets not present to the consumer being one such factor.