Very, very important . But you’re not the only one that have seen such people who are going to argue that stop loss is of no importance, and you did the best thing by letting your friend be, just let him do whatever he wants to do, that’s completely his own business and it has nothing to do with you, but don’t feel sorry for him if he comes later to tell you stories (that’s if shame is going to let him).

I have seen people who don’t use stop loss, I don’t bother asking them why or pressuring them to make use of it, it’s their choice and they can go with it. Stop loss is very important because it helps we traders to stop huge and uncontrollable losses that can happen in this volatile market. If someone says otherwise, then it’s their business, not mine  .