Quite simple, many expecting an explosive entropy of the bitcoin adoption / price but truth is the average folk most common needs and use of money aren't met by bitcoin, this fact goes against the very foundation of any successfully implemented mean of money anytime across recorded history. It really is a political problem at it's core, the deep states run by bankers won't let a viable alternative co-exist in the streets. I have no doubt that with truly liberal and free alien civilizations, the blockchain technology would have attained (for all purposes) universal adoption in a shorter time that the cryptos have been around by now here.
Not everything in this world needs to use Bitcoin but can Bitcoin not be used on some purchases in certain stores? Bitcoin will remain a source of strength for him even though thousands of people do not accept Bitcoin as a transaction tool like Fiat in general. I have never doubted Bitcoin as an alternative but it is still quite difficult to describe Bitcoin into a valid transaction tool like Fiat in general and currently there are several places that receive bitcoin as a means of payment like in El Salvador.
Mainstream is what you mean because if the relationship is carried out according to the concept of the Fiat currency, maybe at this time or the next few years it is still impossible to run. Bitcoin has an advantage in terms of investment and trade even though there is a risk in it when people are involved and perhaps other forces as parties who are able to maintain value.