Convincing the outside world that Bitcoin is a great means of payments is done by using it as such, not by speculating like a bunch of empty headed baboons. Most people say they want to see Bitcoin replace fiat, but they don't actually mean it, they just echo the general sentiment within this ecosystem to be cool and hope that their bags will pump.
Fiat isn't all that bad as day to day currency as long as you avoid debt. Money should be spent without thinking about unit values, and that's one heck of an aspect crypto in its entirety needs to catch up on. As long as fiat has that advantage over Bitcoin, I will continue using fiat more as a day to day currency. Bitcoin is more a currency of the internet in that regard, and that's fine too.