I have much respect for people that can make a positive contribution on YouTube, and there are plenty of them. I have no respect for people that make their money by playing the fool. Just my opinion; I’d rather toil in anonymity and retain my self-respect, than be famous for being an idiot.
I think Scott Devine is one of the better contributors who has learned how to play the game, yet offers actual substance.
A lot of people knock him for the "click-bait" titles of the videos and the aggressive email marketing, but honestly, when you actually watch the video it has a lot of really great content that will make you better musically.
The title "Why 6 String Basses Suck" fulfills the click-bait game aspect of things, but when you watch the video, you learn that 6 string doesn't suck at all but there are all kinds of things you need to consider if you want to play one. And it's all valid stuff.
I've discovered lots of great artists - like Rich Brown - from watching his videos.
Rufus Philpot is another YouTube contributor that puts out amazing instructional videos.
It's definitely possible to create substance along with popularity, but that's hard. Getting views and random clicks is easier.