I once sent a link to a news article to a friend at work. He became angry at me because the link I had sent him was to a malware-infested shit site. It wasn't, but the ads in the site I had intended to send had taken over his browser and made it indistinguishable from a malware link.

That's how showing ads on your site is abuse of the user.

You've just shifted the goalposts significantly and did not really reply in good faith. Showing ads is very different from linking to malware. Especially on YouTube the amount of malware is probably very low since everything is sandboxed.

I think the point is that putting so many ads on a page to the point of it becoming indistinguishable from a malware infested shit site is a form of abuse to the user. I personally agree with this take, if that's what he meant

Showing ads without properly vetting them nor taking responsibility for any malicious ads is not in good faith either.

Advertizement uses your brain power to process stimuli for the purpose of trying to sell you things that you do not need.

You did not ask for your brain to be stimulated like this - what you did ask for is the content that comes after ad. That's the thing you consented to.

Ads abuse your desire to watch something that you want to watch, by cramming in something that you did not want, leeching your precious time and brain-processing energy, in order to sell you something that you did not want to have in the first place.