they have not understood in detail about bitcoin, crypto currency and everything related in it therefore they are not interested in this. others assume that this has a very big risk. so they are frightened to join
That's true, and too bad for them that until now they don't recognize the possible importance of Bitcoin to their life, on how can they be able to survive life without going on very risky investments outside, and in my personal opinion it's their lost and we should not forced them if the things was they weren't ready to believe on this.