Depends - Does your son save instead? If he doesn't, then yes I'd recommend Bitcoin because it's a great way to trick younger people to save. If he does save, then I'd be more cautious but wouldn't dissuade him. If he wants to try, then it's good for him to learn the risks associated with this stuff. For some people, knowing they have something in the market is more emotionally gratifying even if it goes down than to not have anything at all and miss out. Point being, he might feel pressure to get in later down the road due to FOMO which is far worse.