Lack of understanding about bitcoin. When it comes to money, people trust is way to hard to get, some of them automatically think it was some kind of fraud. I also agree that other people accept the fact that they are too late to invest, for reason that bitcoin now is soaring high it was $8250 already and the price is kinda expensive. Another one I agree with is the innovation, some people especially the bank and the governments are not ready to accept the possibilities that bitcoin is going to be the official currencies in the near future they are afraid that someday fiat will be taken over by BTC.
Yes that's right, Lack of understanding is one of the biggest point why bitcoins are being refused of the other people to invest. In my opinion maybe when there is a good orientation of bitcoin or seminar then some of the people might convinced to invest in bitcoins.