That's one way in which ActivityPub wins over ATProto.
It's about as easy and cheap to self-host Mastodon, Pleroma, Misskey, etc... as it is most blog or forum software. It's only resource-intensive if you follow accounts or aggregators that post a ton of media, and even then unlikely to need more than single-digit terabytes of storage.
> It's only resource-intensive if you follow accounts or aggregators that post a ton of media, and even then unlikely to need more than single-digit terabytes of storage.
The exact same thing can be said about running an ATProto AppView vs a PDS.
I think it's the relay that has to be expensive.