If you are going to have it, still better to consider implementation and mechanics early, opposed to try to bolt it on to a mostly finished game. I would agree that intentionally planning to do the latter is idiotic.

That's the answer to the wrong question. You shouldn't even be considering adding monetization into the game. Because you are "fucking evil" if you do.

But the question in the quote was about early versus late addition.

Waiting until the end to add it in is both evil and idiotic