Relying on YouTube is no different to relying on Google, or Amazon, or any service that people build successful businesses on. Yes, there's a risk having a single critical factor, but that doesn't automatically mean the risk is too great to still be worthwhile.
The real problem here is that YouTube has an effective monopoly as the only working platform for monetized online video. If that's the business you're in then you have to use YouTube.
Vimeo has their VOD service. It works very differently, but still...
That is actually a great simile. :)
I can see both sides of the argument, but developing an application and paying to host it on AWS or GCP is different to creating A video and uploading it somewhere for free.
http://uk.businessinsider.com/highest-paid-youtube-stars-201...