Will children be interested in learning the trade? I hope what you say that your friend's child is interested in trading is not a lie, I don't think children will be interested in trading activities and even if there is you will not face any problem dealing with it but that is if you have the right knowledge and not just teaching that trading is a way to make money but also need to tell that can lose monye if not done right.
People can take interest in trading if parents regularly talk about it because children are always a shadow of their parents. I have my own experience that those parents who are doctors so their children also become doctor in future and same is the case with teacher so therefore I want to say that children can take interest in crypto trading too due to the interest of their parents in this field.
One should make an understandable lesson for his children and then teach them each and every single thing about trading so therefore he will surely understand that thing which he Don't know previously. Parents should share their experience with children and try to make a concept for them about risk involved in it so may be the achievement become easy for them.