And he has actually been using his super yacht to do actual ground breaking research on the biology of extremely deep sea creatures.

Not even joking, that yacht has a deep sea submersible, he bought the shipyard so he could direct the refitting of the super yacht to be able to carry and launch it... they've been mapping a trench near Japan, have captured high resolution video and bathymetry... they even appear to have discovered a or maybe a few new species.

https://www.geeky-gadgets.com/gabe-newell-inkfish-unclassified-ocean-creature/

I mean yeah, having a super yacht is ... pretty extra.

But, there are certainly worse ways one could be using it.