The first question has been answered nicely by many other people.
To answer the second question, I think you need to consider the people who are trying to make a living from open source software. The teachers, bloggers, live streamers, book authors (are there still any book authors?). If they manage to jump on the next big wave early, they can become the established expert, and this may lead to money. 4 - Profit.
So many new framework will be met by a few early adopters trying to eke out a living, or maybe make it big. Especially if the new framework promises to solve an issue present in an existing popular framework. And this is impportant... All existing frameworks have different drawbacks. There's always tradeoffs when you design a framework. When you optimize a framework to make X easier, you almost always make Y harder. I don't think there's any way around this.
Then, when the average programmer sees many blog posts about a new framework, they may pick it up, and give it a try. The circle of framework life.