Having to use fiat to use bitcoin is probably enough of a reason to stop A LOT of people from having a desire to use bitcoin. I would assume a lot of people don't care about any of the downsides of fiat so long as it's working for them right now.

I'll give you an example. If someone was about to walk into a coffee shop with $5 to buy a cup of a coffee and you said "hey give me that $5 an ill give you $5 worth of bitcoin and you can buy your coffee with it" MOST people would have zero interest in that because they see no point in it and it's extra one extra step just to buy something they can already buy.

With that said, that's fine. Bitcoin doesn't have to be used by everyone nor would it probably even be practical to use in certain situations, but I do believe everything I just said is a big reason why people would or do have no interest in bitcoin. It just seems pointless to them. 

Even if someones fiat currency crashed, they would still need to use it to use bitcoin if they didn't have any bitcoin. So again they would ask the question "why use bitcoin when I can already use the fiat currency I have".