20 years old and 1000th level?
If it floats their boat, sure, but even the bad DM's I know would trim off about 3 zeros off that level (maybe just 2 zeros).
Of course, now I think of what the treasure value of a character that high would be, and what a character would have to do.
Some friends theorized about this a while back, we came up with a postulate we call "lootworld".
The basic concept is, once a party becomes so high level that they can kill everything on their planet, take it's stuff and XP, they then kill the deities of their world, take their stuff. Then, via spelljamming, they travel to crystal sphere after crystal sphere and kill them and take their stuff, as the entire wealth of worlds is accumulated behind them, so large it not only develops it's own gravity, it retains an atmosphere, and becomes impossible to tow, so a "lootworld" is retained as a homeworld by these ever-levelling super(anti)heroes, as it gathers the entire material weath of the material plane, as well as most of the outer planes, leaving billions and billions of dead mortals and hundreds of dead gods in their wake.
I figure that's what a character has to do to reach Level 1000, especially to get the appropriate treasure level.
The plan starts to break down once overdeities start sealing their Crystal Spheres and severing planar connections to keep everything out, to protect their worlds, or they run into deities with the Salient Divine Abilty combination of Supreme Initiative and Life & Death (i.e. automatically goes first in combat before any non-divine being, and can kill any number of non-divine being at any range including across planar boundaries with no saving throw.), Even though they gave gods stats, they still have a few "I automatically win over mortals" powers. That or their genocide of entire worlds gets them sucked into Ravenloft, where they promptly become Dark Lords and are never seen again, and eventually the overdeities of the pillaged worlds rebuild their ruined spheres, leaving the mythical golden planet of "lootworld" somewhere unknown out there in the cosmos.