I challenge you to pay your bills and buy food with bitcoins only. Oh, you also have to pay taxes with your bitcoins.
Okay, now that we can all agree that it's purely impossible at the moment, there's your answer ^^
Seriously, though, it all depends why you have Bitcoins, and what you're planning to do with it.
I personally want to hold them until I can, well, pay bills, eat and pay taxes with it. Lots of people are doing the same thing, as far as I know !
Furthermore, if nobody converts Bitcoin back to dollar, no one can convert dollars into bitcoin. Don't forget that, for every trade, there's a buyer
and a seller, it's not rocket science
So, yes, not only people are doing it, but we also
need people to do it, and it won't change anytime soon