Maybe it's because people are afraid to change. And conversion is still a bit hard if you don't know how to do it properly.
yeah maybe people are more comfortable using fiat and then they were reluctant to join in bitcoin. there may be the reason. but it seems like only a few people. because bitcoin is not too well known. so the reason is still very rare
In a world of people where used to use fiat money as the main monetary unit. And it is very hard for them if they are just suddenly shift to bitcoins that fast.
And I think only people who are knowledge with computer are easy to get use with bitcoin.