How does gpool make money?

I was watching a Bix livestream and he was asked that question. He didn’t seem to really know. I know they control a huuuge amount of staked theta. It costs money to run servers and keep them running. I mean I just started staking on gpool because keeping my guardian node up became kind of a pain. Seems legit. I get tfuel, it’s pretty close to their calc. Does any one know how they make money? It’s not a charity. How much money do they make? —-thanks in advance