Statistically speaking the biggest blocker for those who are interested in bitcoin is that there is a lack of investor protections currently I don't have a link but I beleive it was a coindesk article but I could be wrong.
For me,i think its the volatility itself that keeps people from getting into cryptocurrency.The price changes from time to time unlike fiat currency that is always fixed.And the fact that the government still not adopted the use of cryptocurrency.