The most expensive thing ever built and maintained is the International Space Station. At $160B over its lifetime, the ISS is a model for the excessively wealthy.
True, it is not primed for self-sustaining flight, and the quarters are very cramped, but a space-faring über-rich individual has to have a Plan B in case they’re not on the same continent as one of their “end of days” bunkers. Those start at $1 million and can run upwards of $300 million.
About the same time as the first private space station comes into service, we will also find that the rocket and tandem-independent space shuttle will also be feasible. Necessity is the mother of invention.
Another easy answer would be Six Feet Under. This show has the most beautiful finale.