You were talking about developers, there are some mods that are/have been also developer here (IIRC).
I've assumed they were talking about the people working on epochtalk (that's where the actual development is taking place, slowly).
Moderators/Staff and Developers are two different pair of shoes, although a single person can be in either of those groups (or in both), they souldn't be mixed up.
At the end of the day it's just a forum, there is not any type of salary or "contract" between the moderators and bitcointalk.org
It's a pretty big forum nowadays and servers need to be paid. Then there's overhead like cloudflare and similar stuff.
On the other hand, the forum has a lot of reserves which are worth big amounts nowadays and the popularity of ICOs keeps the ad auctions going for big money.