@chx @mhoye I was on SPCR back in the day so i Have Opinions?
I think the core of SPCR's problem is that computers got quiet-enough and a large audience of interested people was no longer automatic. What would most people discuss on SPCR these days? Get an SSD and a fanless computer? Few people need to bungee-cord vibrating hard drives or build computers into drawers these days.
There are still niche interests like minimizing coil whine or quieting what I guess is now called retrocomputing. But that's probably not enough to run an entire commercial site on.
SPCR forums could maybe have been cut free of SPCR-dot-com before the domain was sold to a content farm. So then we get into running a server for a hobby community. It's not that expensive to host a phpBB these days, but it does require tech knowledge, which is probably a lesson as well. Mastohost seems to cost around $1-2 per year per active user, that's a price that probably can be covered by member donations. I wonder if you can pay for managed hosting of Lemmy?
Sometimes interests will naturally die out and ultimately that's fine too. People might reorganize into their new, related interests. Maybe it's not SPCR anymore - maybe trading tips about a Nexus 430 PSU is now hashtag-retrocomputing as quietly as possible.