Stats indicate that close to 100 million people use Bitcoin right now. And that figure is more than the user-base of many major fiat currencies such as the Sri Lankan Rupee, Malaysian Ringgit or the Burmese Kyat. So it is already more popular than many of the fiat currencies.
That figure is debatable but even if it's true, that's just around 1.5% of world population.
The major currencies like dollar, euro, rubble etc. are much much more present and used at the world market.