I get your point that a loss in trading isn't a loss but I try to understand that when it becomes a continuous process that's when its describe as a loss. You know some people don't actually take it to themselves that it isn't a loss but instead a learning process and that's because they have different reasons of which they tend to trade but nevertheless what makes a trader successful is being able to understand this process and see it as an opportunity for growth.
It is difficult for traders to always keep this positive mindset, it is indeed the method to go through the grind of trading which never ends.
Some days will be good and some days will be bad - people should review what they did wrong that led to the bad days instead of getting frustrated. Often we are placing trades in the wrong direction or we are not giving it enough time to bounce back.
But there is still a limit to how much one can endure here. Trading is not for everyone specially day trading.