how does make money?

In the sdmb improvement thread on the last page the discussions are about how much it costs to run a mb like this

And a lot of users thought that it wouldn’t take much to run a place like this because is free and just has a banner or two on the hosted sites and we had the reader and subs ect …….

Now even tho ive been on a dozen or so pb hosted sites (the imaginary RP wrestling feds I play love the place) ive never needed or thought about a subscription …
So is it just that cheap to run ? or does something bigger own it and just keeps it free for goodwill?

Moving to GQ

Part of the answer is in the premium features, which presumably aren’t free.

“Premium Features — We offer additional premium forum options including the ability to use your own custom domain name, remove advertising from your forum, and the ability to change your forum URL.”