If money weren't an issue, I could understand it. You could invite friends and/or family to come over and stay as long as they'd like. If you wanted some time to yourself, they wouldn't even have to leave, they could just stay in one of the guest-houses for a while.
You could have any kind of special hobby room you wanted. Martial arts dojo? Sure. Home theater? Sure. Laser tag room? Sure. Dance studio? Why not? Kitchen with every kind of tool, multiple ovens, multiple stoves? Of course! Workshop? Why not. Cozy knitting room with every kind of yarn imaginable? Great!
Some kind of good cause you wanted to support? Give them an entire wing of the place. Feel bad for a marginalized group like refugees? Hand over one of the many buildings for their use.
Overall, the world would probably be a better place if no person / family had this much wealth. But, that doesn't mean that I'd hate to have a place like that if I happened to be insanely wealthy.