> My wife is a content creator on YT and hasn’t spent a dime on advertising.

Is your wife a representative sample of all Youtubers? If not, your datum is irrelevant.

> unless your audience is very tech oriented, they’re not going to switch off whatever platform the ads are on to watch videos hosted elsewhere.

Having now witnessed multiple creators hop from one platform to another and drag their audiences with them because they're JUST THAT ENTERTAINING... no, you're wrong. People will gladly follow artists to a better platform if it means they're able to make a living and/or not be censored.