Imagine 20 millions BTC (all btcs available rounded) for 10 billions of people (all people on earth in near future rounded.
Average owner would posses 20,000,000 / 10,000,000,000 = 0.002 BTC. Today it does not mean anything but once such small amount would be average amount hold by one person.
So if we take it like monthly sallarry lets say $2000
0.002 BTC = $2000
1 BTC = $1,000,000
Imagine that. :)