I'm going to attempt an answer, but as with all things this is only my perspective and I obviously don't speak for all HN readers.
HN is largely for founders who want to build things. That's certainly how it started, and there's still traces of that vibe around in the Show HN and startup-y threads. There's a lot more going on here now, like more code topics, AI, electric vehicles, environmental things, a little futurism, etc, but the core is and always has been startups. In itself that doesn't rule out having a reasonable conversation about cryptocurrency. There are a lot of opportunities around crypto. There are startups to found, and pain points to solve. The problem is that crypto has three significant problems for HN readers:
Firstly, a lot of people trying to make a living in crypto are purely speculating. They're not building anything. They're simply trying to "buy low, sell high". Entrepreneurs, in general, don't really have much respect for that. Founders admire and respect people who go out, found a business, and build something real that solves a real problem, even if it's a problem we don't have ourselves. Leeching off the system isn't a skill.
Secondly, a lot of crypto isn't solving a real problem. It's essentially trying to be "digital gold", but without the usefulness of gold. It's only a store of value. There absolutely are good uses for crypto, and even for things like NFTs, but most of the speculation isn't about those things. It's only the "buy low, sell high" side of things. HN is not a forex or trading forum. Again, we respect people who make things.
Lastly, no matter how you cut it, and even with the latest lightning and taproot and proof-of-stake tech considered, crypto has a massive set of problems to still to solve with its environmental, regulatory, and money-laundering issues. To be honest, to me, they look pretty unsolvable. I have a decent understanding of the tech and I can't see how you can build an anonymous system for transferring wealth around that requires significant bandwidth and CPU and not screw the planet by providing a service for drug dealers and terrorists. The fact people are trying is awesome, but I suspect they'll fail. All of the upsides of crypto are also upsides for people who want to use it for bad reasons.
All in all, cryptocurrencies are an interesting idea, and the tech seems like it could have some valid applications, but the downsides are huge. A lot of the pro-crypto people involved don't want to acknowledge that. A lot of the anti-crypto people can't see that the tech could be useful. There's no middle-ground. That makes talking about it pretty boring.