But that's not the problem
That is the problem
And it is unlikely to get resolved in the future, if ever. People are not going to use Bitcoin as a payment method en masse simply because it is too good for this purpose. The bad money always drives out the good money from circulation (so-called Gresham's law). And in this case fiat is that bad money, while Bitcoin is the good money. In other words, people would always try to spend fiat first just because they value Bitcoin higher and prefer to keep their precious coins to themselves, while spending dollars (or whatever)