Heard of blogging, how about vlogging?
There are the obvious political reasons and some forward fake news videos to reinforce their own biases, but do you realize the money that is being made by these viral posts that get everyone in a frenzy? How? Why, glad you asked.
You did didn't you? :-)
The first one to benefit is the outlet that enables the video maker to post their creation. They sell ads on those pages, improve their traffic reports and thereby enhance their ability to sell more adds. Some create their own site and put adds on their site as well as affiliate links. (Links that pay for the traffic they send to someone else.)
Then there are those who link the video or pass it along on their social networking site (think FaceBook). Some of those benefit directly but most probably only benefit by the increase in traffic to and from their sites or again, to reinforce their own beliefs.
But if you are not necessarily politically bent, why would you want to produce and post a video on YoutTube? Some might just enjoy making and producing help videos or travel videos but if you start putting a bunch out, you probably have something a bit more lucrative in mind..
When you get to a certain number of views, referrals, etc. YouTube will consider adding you to the contributors that THEY pay for uploading videos. There are MILLIONAIRES out there who have done just that. Sound easy? Doing them at your pace could be somewhat easy, but to make big money, you have to produce hundreds if not thousands AND you have to get views.
So why make outrageous, unsubstantiated, false news? Because there are millions of us out there who will believe it and pass it on. You can almost hear the coins dropping. Search for youtube millionaires 2016 for a current idea.