I think it’s more sustainable then Facebook ,Twitter and others. Why? Because it’s federated! if one instance goes bankrupt or shuts down for whatever reason it doesn’t close down the entire program. If anything, at worst a portion of Lemy communities would get erased from history. Lemmy in reality is really just an interface, with a bunch of different instances combined to provide the content. The cost is actually cheaper then other social platforms from the last 10 years+ like Facebook because in a way the cost for the “service” is divided by all the different instances hosted by volunteers,

I hope this makes sense, if any questions do ask.