> Or maybe people are naturally more attracted to the extremes [..] What if youtube was just giving people what they want
That's part of it, but I think the point is more subtle. YouTube shows the content that will keep people on YouTube (to maximize advertising), but that doesn't mean it's what they most want.
Given good or bad news, we may prefer the good but spend more time on the bad, even if the bad news is something that's irrational to worry about.
The way to get people to spend more time on YouTube may be to make them worry more, care more, and overall be more involved in the topic by showing more extreme aspects of it. That may be more exploiting human psychology (perhaps unintentionally) than giving people what they want, or maybe it's giving our darker sides what they want.