I agree that they should realize it's a volatile system and prepare for downswings, but that doesn't make them beggars.
There are many popular creators on YouTube earning an honest full-time living from the YouTube platform, some even have more lucrative relationships with YouTube(e.g. Slo Mo Guys, Vsauce). It's hyperbole to compare them to beggars on the street. Is that income absolutely secure? No, but that seems to kinda be the trend we're heading towards, where fewer jobs provide income security. Should YouTube be more open and transparent about demonetizing content? Yes, especially considering their effective monopoly on the indie video-on-demand scene, and parent Google's effective monopoly on internet ads.
I'm not trying to make a dig at anyone - I'm describing reality and it's upsetting a lot of people who feel entitled to ad revenue. I honestly hope YouTube just does away with their partner program altogether.
As for YouTube careers - I couldn't agree more that many creators are full-time and put their time and energy into making content. The Slo Mo Guys, VSauce, etc are all making money outside of Adsense. They've done what Philip Defranco often tells people to do - diversify where you're getting your money from.
My whole point is that being a YouTube creator or a blogger is a perfectly fine profession - but that requires work to monetize your product and/or direct support from your subscribers/readers.
I am a huge proponent of users in general creating and participating in services that truly meet our needs and wants rather than going all in and hitching ourselves to a multinational corporation that has advertisers and board members to please.
I honestly think we're on the same side of this argument. I just don't think the answer is in expecting YouTube to take care of us.
I know a lot of people want to nationalize YouTube/Google, but unless/until that happens (and unless/until their IP becomes free & open source), we cannot count on them.
But I agree on the rest of your point, relying on advertising and third-party services is unreasonable.
EDIT: many people are upset by the panhandling comparison. I just meant that as a juxtaposition to those saying "it's like being fired". It was meant as an analogy - no intent to insult anyone (YouTubers and beggars alike). A better analogy would be a musician who was paid to perform in a bar, and the bar owner tells them "you can still play here all you want, but we're no longer going to pay you." (mind you - they are not saying "you have to continue playing here and do it for free")