I don't think this is entirely your friend's fault, it means that his 2 friends don't have any knowledge of crypto, if they are advised and follow them. those who do not understand risk but optimistically invest, until they finally experience disappointment. Therefore, in investing in crypto, it is permissible to accept advice from others, but personal analysis must be used to determine our steps
They don't have a knowledge in crypto and that is the reason why they seek advice to his friend but maybe his friend didn't give them a disclaimer that what he taught are not 100 percent guaranteed to work. That was his mistake there and now he is being blamed for their losses but time heals, if they are a true friend they will not exchange that friendship for money that is lost and besides, his friend can do something like paying them and continue to give them a much proper advice.
Now that this happens I think his friends are now going to be more cautious next time and they will now probably learn how to make their own research.