I could develop a social network that “scales” in way less than three months, just working alone. A few days for the web front-end (with a few days of tweaking a bit later, and then a week of actually making it work). A couple of weeks for the ActivityPub implementation. Five minutes… perhaps 15, if I want to double-check my work, for the SQLite database. Then another week of making sure everything fit together nicely; might be able to do it in two months, actually.

It wouldn't be pretty, and it wouldn't cache images locally (which is a problem from a privacy point of view), but it would work, and it would scale just as well as the rest of the Fediverse.