This is a bell curve. We are by mathematical definition well within the "innovator" portion of that curve,
as less than 1% of the world's population currently uses Bitcoin.I have marked 0.5% for you in red, to give you an idea of just how early we are in this game.
with DELL and paypal and other big names jumping in, we are at the Early Majority.
It turns out Bitcoin is not limited to use by American companies, but is in fact a global currency useable to all businesses and all people. You must consider the fraction of potential use cases, be scientific.
You make the assumption that 100% of the world's population will use bitcoins eventually. That's just not gonna happen.
Just 39% of the world population is currently using the Internet.