It's fascinating the inner struggle of someone so successful yet who still feels the need to find something bigger to accomplish, a higher mountain to climb.
I feel for him, since life is not easy for most of us and he purposefully tries to make it harder for him. But I also think, that the meaning he so desperately wants can come from other things than just building bigger companies with bigger stakes. There's always a bigger stage play, a bigger house to build or company to create.
For me art is quite enjoyable, as there are no specific limits to your proficiency or rules to play by (well there are some very good guidelines). It just is what it is to amuse you, make the time go a little faster and perhaps amuse other people too. Or friends, children and family in general, relationships that aren't bound by status or money but by mutual enjoyment of each other's company.
Maybe what Peter needs to do is just go away for a while and travel the world, and find out what it actually means to be human in broader sense. Just put everything on hold and go somewhere, with a fake name if you must and just hang out with random people and experience their reality for a while. It isn't the end-goal to have "made something" but the trip to get there, even if it sounds like a cliche. I'm sure he could too find something satisfying that isn't just building companies. Or maybe I'm wrong, as I've never met the guy and don't know him personally. And building a more meaningful and successful company must sound like fun too. It's just that is not all that there is.