Buy a RocketLab Electron launch and insert a literal hunk of lead or a beam reflector cube into geostationary graveyard orbit. They never had GTO launches before, let alone direct GEO, and I think no one had ever done an intentionally passive object into GEO let alone commissioned by an individual, it'll be an all around achievement. It's going to stay there for a geological timescale with negligible risk of space junk and gets its own Gunter's Space Page and Wikipedia article with legitimate interest from public.

There are countless stupid fun in the world that money can do that isn't about buying out a human or legally punching an NPC in face. As well as legit meaningful businesses that may or may not make money but kinda fun and useful. The fact that this person is being unable to come up with such a task suggests existence of a problem, though I wouldn't know if it's mental or developmental or physical or circumstantial.