Bitcoin's utility is fast, cheap, permissionless transfers in a defined inflation structure.

As more and more people come to value and desire those attributes its acceptance will spread and universality will increase.

And yes, I know people will argue with how fast, how cheap, how permissionless. Other cryptos have advantages over BTC in these areas.

The comparison to make though is BTC vs fiat. Sending my own money from my account at one bank to my account at another bank takes 3 business days to settle and I'm paying bank fees (monthly maintenance, cost of checks, potential deposit fees if I do it too often, etc).

And that's just with my own accounts. Try sending 10 million dollars to Cuba and see how long that takes and the costs of doing so.