Because YouTube is focused on a lot of different types of content at the same time, it has many opportunities, and the hardest thing is to figure out which ones you shouldn't do, and focus on the ones you should.
Silicon Valley builds its bridges on abundance. Abundant bits of information floating out there, writing great programs to process it, then giving people a lot of useful tools to use it.
By creating fantastic content and spending zero time on audience development, you are certain that you will not succeed on YouTube. You have to focus on audience development as much as you focus on creating content.
Entertainment works by withholding content with the purpose of increasing its value. And, when you think about it, those two are just vastly different approaches, but they can be bridged.