This. It costs hundreds of millions per year to develop a web renderer. The security expertise required in particular is immense.
People have made clear they will not pay for browsers. At the same time, Mozilla doesn't want to hoover up mountains of personally identifiable information like Google and MS do.
People hate Mozilla for doing what they can to make money, and they also hate the idea of paying.
I understand the frustration, but I genuinely don't know what the community expects.
Don't get me wrong, I don't agree with or see sense in every Mozilla decision, but people act like they're satan incarnate and it's just ridiculous.