I can't understand why people here thinks that bitcoin isn't global currency but it will become in future.
Wallet is available for everyone, you don'y need bank account and no one controls your transactions, it's first cryptocurrency and most known and trustful, ICO's are mostly in bitcoin and mining datacenters are worldwidely, so how can't you to call it global currency?
The answer to your question is simple. Because hardly anyone is accepting Bitcoin. How can it be a currency if i am not able to pay my rent? How can it be a currency if i can not buy my bread with it?
I don't particularly disagree with your point
But, on the other hand, if you lived outside the US, could you pay with the US dollars your utility bills elsewhere directly (barring some small countries which use the dollar as their official currency)? I guess you can't, but could you thus consider dollars as not a global currency? If you can't either, was is global currency then? There are specific cases where you can pay with dollars, but basically the same can be said about Bitcoin as well. For example, how many online casinos use the US dollar (or any other fiat, for that matter) as a money token for gambling? I don't think that a lot, but I think that the volume gambled in Bitcoin online casinos by far exceeds the volume gambled in fiat ones (compared on the dollar basis, of course)