I can't speak for everyone, but I come from a precious metal background. I see Bitcoin as a digital upgrade for gold.
I can retain my privacy, which I appreciate.
I can avoid the whims of central bankers and their fiat inflation policies.
I can avoid normal banks who tend to freeze account for pretty much any reason under the sun.
I can avoid middlemen when I want to send money to a friend down the street or on the other side of the globe.
These are all very good reasons to use bitcoins and the same reasons why I would like to see bitcoins become a currency I can realistically but dinner or pay rent with. But most people don't care about privacy. Most people use Chrome and Facebook with their real names and actually like 'personalized ads'.
Most people also do not know nor want to know anything about their own financial systems. As long as it is still easier for them to pay in dollars they will continue to do so, Internet Explorer is the second most popular browser because most people don't care enough to find a better way to do things.
If it becomes easier to use BTC than fiat currency then certainly these people will transition over but right now BTC reside in a very niche market for "those crazy anarchist libertarian people".
Bitcoins must offer some sort of incentive people care about in order to be adopted as a useable currency. And for the average user they do not.
Although I guess it would be very fair to say at least some people will always want bitcoins (or some equivalent cryptocurrency) and there might be at least some sort of market for them which seems to be what OP is asking anyways.
