A lesson can always achieve through losses but sometime those individuals who fails to attain profit thing that they cannot do it and leave trading and investment instead of thinking that they will not do the same thing. One should remember that at start he will make lots of mistakes and he will overcome these mistakes through getting knowledge. At start I did not have patience and because of this behavior I lost money at start but now I am familiar with all the things related to trading and investment.
Learning from mistakes is one of the best ways to minimize losses and improve in terms of knowledge. Well you're right, it's not uncommon for someone to leave when they experience a loss for the first time, they think they can't do it and look for various reasons to justify their position. Without them realizing that this is a valuable experience for the initial success. That's why I suggest beginners should get to know the field first and the various risks they will face when everything is running. To be honest, I have been in a position like this and I choose to stay because I believe this is the beginning of my success in the future.