21mil / 8billion = 0.0026 btc per human You could start by saying this is one person's "share," but also if you factor in big holders like Saylor then the median "share" after hyperbitcoinization would be much smaller than 0.0026. Considering that this currently costs $80, most people who read this site could get way way more than that.
Another way to slice it is to make a bitcoin price target. Let's say it goes to two million in 2019 dollars. A fat stack could be anything above $50k in 2019 dollars, depending on how ambitious you are, where you live, etc. That would come out to $775 at today's prices.