Yeah Me too. I experienced that too. I gained so much but it the end I have loss a lot. Maybe you cannot blink of an eye and make watch to market.
Well, it means that you are learning from your mistakes and making those failure as a ground for you to be enlightened, I myself don't let my big losses in life as failure but as a foundation for me to become braver and can handle and face things and challenges in the future.
It is just depends upon your thinking ability, if you are thinking rightly then you will never follow this perception. If you are making wrong decisions then you follow this perception, though it is an old perception too. It is true for those who are working without knowledge and face with loss and then slowly their minds start working and learn from their mistakes but we know that the modern world is very fast and this perception is not relevant here.