Parents needs to be watchful of their teenage children as that is the critical stage of raising a child, they learn fast at that age and get distracted too. Just imagine if the young man had genuinely put his effort into learning tech properly, he would have gone far with his skills. If you're child is talking about bitcoin and he/she seems to know more about it, it's good to look at what exactly they are doing that involves bitcoin, just just running along with what you've been told, else your teenage child will be directly under your roof and will be defrauding people online.
To some extent parents are to be blame entire morespecially in the scenario the op just explained. Some times children may decide to toll the wrong path, may be as a result of peer groups influence. The only way most of this teenage will stay clear in indulging in cyber crime is through awareness because I believe most of them don't really know the consequences of what they are doing. What they is a good orientation, they should be made to understand the consequences of cyber crime. Most parents don't really know much about tech and as such they won't be able to monitor the activities of there children online