No there doesn't. Whatever you can't spend goes towards making sure your descendants are taken care of. Or you can donate it to the various charitable organizations of your choosing.
If we make it as easy as we do to become incredibly wealthy, we should make it just as hard to stay wealthy.
That doesn't logically follow. I think that a great portion of what makes wealthy people wealthy is blind luck. That's not to say that Jeff Bazos isn't a great businessman or a hard worker, but I'm not convinced he's the greatest businessman there is.
What possible reason could one have for making it “hard” to stay wealthy, other than pure spite and jealousy? How does it benefit society in any way?