We learn new things when we fail. We learn nothing if we don't fail. I don't believe, "You Learn More from Losses than from Wins" because that's incorrect. One can learn both ways. In fact, I learnt more from my wins than I did from losses. You talked about losses like anyone wants to have them and then readjust from such. If there's anything losses will even do to beginners, it's to scare and discourage while introducing them to reality.
When one is permanently on the winning side, he has nothing to worry about, but when one fails, he will have thousand questions that needs an answer as to why he failed, and from this he learns. But in the case of quitting after failing, I think it will depends on mindset. It is always helpful to try a different strategy. A newbie who has been briefed on what trading is all about will not quit after losing. Of course trading involves loses but the better side of loses is figuring out a new way of approach. No matter how productive and consistent a strategy is, No matter how long the winning streak a strategy brings, it will someday fail in a long run. And when ever it fails, we learn.