This seems like an odd claim _especially_ for indie games. Indie games tend to already have trouble attracting buyers, it feels like anyone considering pirating it would just move on if they couldn't do so.
0. https://www.gamedeveloper.com/business/so-52-45-of-people-pl...
Personally, Steam's about where I draw the line. They've given me enough value as an ecosystem and their native 'DRM' doesn't seem that obtrusive, so they've got a lot of my money over the years.
I've regretted every single time I happened to buy a game, which turned out to have other DRM or any form of 'anti cheat' client side. They just never work in the long run.
It's a shame that OP didn't add a tracker to the pirate plea button. I would wager that he made practically zero sales from it - looking at how well donations seem to work in software development in general. I think that this is why microtransactions work well. They give away a nerfed version of the game for free, and after the player formed an attachment to it, the game can be upgraded for a price. In a way, this is a much more human design, than forking up the entire cost in advance.
I pirated GTA5 to test it on my machine back in the days. Textures popped in seconds later because the HDD was way too slow to handle the game. I prefer pirating a game over dealing with refunds. I have it for free from Epic. Would I buy it now? No. I don't like the game at all after playing for 4 hours.
What is my favorite single player game? Cyberpunk. Do I share that information? Yes.
My thought regarding indie games were successful ones though. Something like Celeste or Balatro.