Is bitcoin a global currency?

[True Federalist (진정한 연방 주의자)]

Certainly not to the extent the US dollar is. Save in a few marginal places such as North Korea, you'll find at most minor difficulty spending US currency. Bitcoin is a specialist medium of exchange with a built-in infrastructure limitation that will prevent it ever seeing widespread use. The blockchain that provides bitcoins their anonymity and decentralized nature can't handle even a mere million transactions per day. Even the modest yet controversial efforts to improve throughput won't make it capable of handling the billions of daily transactions that would be needed to make it a real global currency.

It's possible that a future digital currency could solve the problems Bitcoin inherently has, but I'm skeptical. Bitcoin makes some sense for its niche market, but a digital currency that solves the problems that prevent it ever seeing widespread use would cause it to lose its luster to the miners that make the Bitcoin network possible.