If you tell your friends and family about Bitcoin without giving them any sort of in-depth financial advice and they go ahead and invest, how do you deal with it when the market dips very low and they silently blame you for losing them money.
Yes, we all know that investing in bitcoins is risky, but we can't control that risk. When my friends ask me about bitcoin, I don't want to persuade them to invest in bitcoin, because I'm not sure I can guarantee that they won't lose money.