Mistake most people tend to make is to think losing is not part of a trade, of course it is, and it is how you manage the risks of losing to the reward you get per trade that matters. Now, it is not your fault if you lose, if you anticipated something and it does not work out as planned which made your stop loss to hit.

However, it is most definitely anyone's fault if they never had a stop loss in their plan and they are now in a big loss. These are totally two different case scenarios as far as I am concerned. Anyone that wants to trade, and does not stick it  in their head, that they have to account for losses too, are not ready to trade at all.