7,000,000,000 people in the world but only 21,000,000 Bitcoins.
Interesting thoughts, but you're missing something.
Bitcoins can be easily replaced, they have no intrinsic value. Bitcoins are good for cheap money transfers, etc. But no one will ever pay 1000$. They'll just switch to LTC or some other fancy currency.
People will pay +$1000 for 1BTC (It has already been there).
If the exchange was that high people would still pay USD for BTC because you do not need to purchase "whole" coins; they can be purchased in decimal amounts.