You should tell them how you earn with bitcoin and make them aware about what you've been doing for 6 years is not that simple. The only reason why those parents agreed to teach their kids is they think that you can easily earn from it since you are doing it at the comfort of your home. They should be aware that bitcoin and other cryptocurrencies are not a get rich-quick scheme like how some of the investment schemes portray it.
I strongly agree to it because being involved in a crypto world needs a long time or run for experience and a year isn't enough to full understand. The market seems to be the very subject of it and it requires a lot of patience and understanding. If a person really wants to learn he or she will make extra time to get information.