At what point did she wrongfully decide YouTube owed her anything?
It's not like it's one way transfer of value from companies to users.
So why your rhetorical question?
It's orthogonal question to the effectiveness of going somewhere and shooting some people.
If not, why does YT owe her anything?
The situation is different (AFAIK she lives in the US which has far fewer job protection policies, and earning a living through YouTube doesn’t count as an employer-employee relation), but there are analogies. Few countries and jobs have so little job security as being a YouTuber.
And unless this information is somehow hidden from anyone who consensually enters into a relationship with YouTube, this is not really a good point
Why does anyone think that what pays today must by definition also pay tomorrow, or else some grave ethical transgression has occurred?
Job security is an illusion (or a gross inefficiency, choose one)