In a few years 80 million may not be what it seems to be. Our central bank and the world in general central banks are printing like crazy, but don't be worried.... Every man made currency has reverted to zero the dollar will be no different.
If I had 80 million, I’d buy everything I needed to sustain off grid—-solar, wind, water power, artesian well, fireplaces and wood burners, batteries and generators, a greenhouse for fruits and vegetables, a chicken coop, etc. The leftover I’d split up—cash, gold, silver, diamonds, oil, water, etc.
As to the OP, yeah 80 sounds good, but since we’re talking fantasy, how about a billion? Cover all the bases AND help others!
Nothing’s perfect, nothing’s forever, but...