Some of this post is true, but it is very much overoptimistic.
Xenforo costs roughly 325 bucks to get the plugins necessary to run this site.
Web hosting runs at least a hundred dollars a month here as of right now. I know who their provider is, and my understanding is we are on dedicated hardware. And the kicker? The site is still struggling with the load. Put this onto shared hosting, and we couldn't handle 1/10th of the database the site has.
Cloudflare alone is running this site 25 dollars a month.
All of the fringe stuff you aren't thinking about for scaling is what ends up killing you.
There are ten recurring bills that are required to keep the lights on here.