can someone start up a server on their personal laptop?

Anyone can start a lemmy instance on their Raspberry micro computer, personal laptop, dedicated home server, script-compatible NAS’es and on and on.

But most Lemmy instances are hosted on VPS’s for stability and scaleability.

The other problem is that eventually you will have only a few large servers because people who join will want as much content as possible.

This is an issue I’ve talked about before with the general response of “It’ll sort itself out”. Now, a few years later it’s total fragmentation and a budding centralization with the new “megainstances”.

I envision special interest servers that are monolithic in community nature, dominating certain topics. Unless there’s some sort of mitigation, like a federated subscription list+multi"reddits" or something similar.

This is correct, I can find old posts from an account I deleted ages ago from an instance that doesn’t exist still floating around those we federated with.