just because you reach the whole world doesn't necessarily mean there's a good way to monetize it, at least without losing what makes the service attractive.

Sure they could start slapping ads on everything, even paywall the site but at the end of the day there'd be significant competition eroding profits.

Twitter almost makes more sense as an open protocol than a commercial service, which is basically what Mastodon is. It's even what Dorsey wanted to do at one point with Bluesky, not sure if that's still alive.