I don't hate it, but they've lost their original purpose. Once a lot of people started flooding in a lot of them while the projects were good at first ultimately turned into a huge cult following lead by certain "influencers". There's also a lot of concerns for the environment with them. That's definitely something that can be worked on though. It will never be energy free but there can be optimizations made and renewable energy can be used.

It's mainly the perception. Just a few years ago everyone loved cryptocurrencies but when people started talking about the environment with them, people started turning coat. Some people, this is also my stance, just want certain things to be crypto and some not. I don't want to have to think about money while I browse the internet and blockchain interactions.

A lot of the Firefox users in particular are mad at Mozilla especially about the environmental concern, because Mozilla has climate commitments that they've made and people feel like they're betraying those by accepting crypto donations. (https://blog.mozilla.org/en/mozilla/mozillas-climate-commitments/).

Another major reason is just simply that people don't like change and are worried about companies abusing cryptocurrency for their own gain.

Keep in mind with me making this I'm speaking from the perspective of someone who hasn't been into crypto for about two years now, but was before. I may have some facts wrong but these are the reasons I've gathered on why people are upset at Mozilla over this. And some for crypto as a whole.