Firstly, let's assume that we are upset with twitter firings enough to quit twitter. Moderators, accessibility teams, etc - we consider them important enough that we leave when they go, and go to mastadon? Which has how many content moderators?
I'm no fan of elons style, but he's not wrong that a company losing 4m a day is sustainable. And saddled with 13b of new debt to pay off the old owners won't help.
Advertising won't save twitter. That's been tried and failed.
While there are edge cases where twitter is valuable, the vast majority is just noise, and not in a good way. The one-line sound bite has been co-opted by politicians and celebrities, to to little more than gain attention. It panders to the over-simplification, it eschews serious discussion of nuanced viewpoints. It is driven by those seeking attention, when absolutely any attention will do.
It is the bottom that internet communities raced to. Overall I think a world without twitter is better than a world with twitter, regardless of which platform it ends up on.