If you hold a coin for a long time and invest a large amount there and lose it, then it is really painful. And if you decide to harm others emotionally from there, it will be a wrong decision and it comes from emotions. In this situation, your friend needs to refresh his mind and for this he needs to visit a place surrounded by natural beauty so that he can refresh his mind. After that, he should focus on his work again and start everything anew. People make decisions emotionally, which are never good, although they cannot feel it at that time. So as a friend, you should stand by him, comfort him about the issues and if necessary, go on a tour with him, so that he will return to normal.
I agree with you because 10 BTC is not just a word of mouth, it is the life savings of many. So in this case I would like to add another thing, he should stay away from the crypto world at least for a while. Then he can at least calm his mind and should refrain from looking at his wallet again and again, because if he wants, he can see his wallet balance in his blockchain explorer and his suffering can increase from there. Better yet, if he moves away from the crypto space for a little refreshment, then it is somewhat easier for him to forget it. Although it is not possible to forget it completely, since it is a huge shock.