Story time

My nephew, who is around 15 years old, has gained knowledge about bitcoin and cryptocurrencies through exposure to discussions between his father (my brother) and me, as we frequently talk about bitcoin. Whenever he has free time from school or chores, we allow him to listen in on our conversations and ask any curious questions he may have. For instance, he often asks questions like, "Uncle, what is bitcoin?" or "Is it a type of currency? Can I have one?" We do our best to explain the concept to him, but sometimes he grasps it easily while other times he struggles to understand. What I do know is that this young boy is displaying a keen interest in the subject.
Recently, he expressed his frustration about his teacher and classmates labeling bitcoin as a ponzi scheme or a scam each time he talks about it. I'm seeking a variety of advice that I can offer to my nephew in this situation. Although his father suggested that he should stop discussing bitcoin, I don't feel comfortable with that approach. What are your thoughts on this matter?
As a person who knew bitcoin during times where scammers are everywhere, and people falls to their scheme, you should tell him to ignore those people why? just like the people who bash bitcoin before they will eventually jump in when its too late, instead of wasting his energy and effort to those people focus on increasing his knowledge and share it to people who have interest on it, although its natural for people to say its a scam getting mad will not bring him to the top, ignoring them and showing them the result is the best way for them to regret what they said, and they will eventually regret it.