Oh, it's far more terrifying that the natural result of being good at feeding people things that you can determine that they will respond well to is that you will progressively feed them more extreme content, because tragedy of the commons is much scarier than mustache twirling villains.

At the point when you recognize this and then choose to proceed apace, you become a “mustache twirling villain.” YouTube crossed that threshold a long, long time ago.

Because our systems are already optimized in a hundred different terrifying ways.

There is a review posted around here of the book 'seeing like a state' that talks about how the modern world is not optimized for human needs, but the needs of the state to collect tax. It makes many good arguments on why it is the case.

Google didn't "expressly design" YouTube to manipulate people, come on, that's a wildly uncharitable view. Virtually all popular content hosting sites have some form of recommendation system - because people like them. Claiming it's all a conspiracy to manipulate people is the same school of thought that says all advertising is manipulation, all businesses are run by psychopaths, etc. It's fairytale stuff.