It is not about paying back publishers, there are plenty of games that without DRM would still make ton of money. But it is a simple math for them, if they can spend 100k on DRM and make 1mil back because of reduced piracy they will go for it. It really doesn't matter if the game made 200mil so that 1 mil is a drop in a pool.
Technically you're right, I made a mistake in my oversimplification of the dynamics between publisher and developer.
DRM doesn't exist to ensure the publisher makes back their investment or even protect sales for the lifetime of the game, its real purpose is to protect the week 1 sales; publishers refer to that number during investment calls (and conveniently forget to mention it when it's absolute shit) to show investors how wise an investment it was, they care less about sales after that because the real money-maker is the recurring revenue from microtransactions.
Which loops me back to my criticism of Helius: that situation doesn't apply to him at all, he doesn't need to show strong first week sales is to his patrons, they just want a good game, so DRM is unnecessary. He doesn't even need an always-online games-as-a-service BS for recurring revenue
given he already has a recurring revenue source in the form of 16.5k patrons, he could literally string them along another 8 years by promising DLCs and expansion packs there without having to deal with maintaining a server for his circle-jerk lobbies.
New video (Elizabeth/Galatea) enjoy
I swear, the modeler and animator can probably make more if they'd just set up their own Patreon/Pixiv Fanbox account or make movie packs to sell on DLsite.