Let's say you had billions to do whatever you wanted, what would you do?

Personally, I'd have a whole personal virgin megastore to live in, to fill with physical media, whether it be CDs, DVDs, Blurays, 4k blurays, vinyl and even cassette. Connect that to personal listening room and also a home theater, maybe gaming room... and of course have bathroom, bedroom and kitchen since those are kind of mandatory. The basement would probably have an indoor playground, complete with slides into Ballpits, because I still think that stuff is cool, why not go wacky wild?