Your luxurious life-style re. water, OTOH, does not save you from uninsanity. It is only a matter of time until Hitler's piss molecules disperse everywhere.
I find the argument that "we're drinking the same water that Julius Caesar drank" a bit specious at best. That may be possible, assuming that said water molecules have survived intact. But water is used by living organisms and incorporated into various organic compounds; the molecule is split. Thus, what are the chances of finding the same pair of hydrogen and single oxygen atom that comprised the original? All one can really say is that we might share some atoms in common with Moses.
Well, maybe it's accurate after all. There are so many water molecules per litre that if you mix a litre uniformly back into the ocean and dip out another one, then you get some of the same molecules back. So it seems reasonable that one might drink some of JC's molecules and then piss them back. Not only that, but it might well happen every time you take a drink.
Sort the specified water molecules out and auction them off! You'll make a fortune.
Which goes to the root of something ordinary "once owned by" some famous person going for outrageous amounts of money. It's basically a belief in spiritualism.
Missed opportunity. Perhaps some enterprising soul wants to collect Elon's urine and auction it off after his mortal departure. "Get yours while you can--they're not making any more of this stuff."