Youtube rarely knows what ads to show me. I don't make enough money to visit Saudi Arabia or buy a luxury EV, and I don't have Crohn's Disease, but those are the ads I get shown. If the ads were relevant it might be a different story, and that's supposed to be the entire point of targeted/personalized ads, but it routinely fails to deliver.
But you don't just buy more videos on YouTube. The videos are mostly free. So they have to advertise other stuff at you.
In case of YouTube it should be guiding me towards interesting content creator videos about things I might buy (like video games I'm interested in). YouTube just needs to find a way to get a chunk of my purchase money from Valve if I end up buying a game on Steam after watching a Let's Play video for that game on YouTube.
But that's something for YouTube to figure out, not me ;)
But that's not even the issue. For instance the entire Steam platform is built around advertising computer games to me that I might be interested in, and I have zero issue with that. I discovered lots of interesting games by following Steam's recommendations which I then bought and enjoyed.
I also accept "sponsor ads" that are directly integrated into YouTube content creator videos, absolutely nothing wrong with that.
What's entirely pointless is YouTube showing me some fancy lifestyle ad that's entirely unrelated to my "lifestyle" and also unrelated to the video that I actually wanted to watch instead.