Do We Really Understand This Probability Game?

I was just reading "Trading In The Zone" by Mark Douglas, and man I came across something that is so good.

Trading In The Zone Excerpt

It is about trading as a probability game, about finding an edge and taking it every time it occurs. Easily said, but do we really understand it? Suppose after intense back-testing a mechanical trader derived Setup A which he knows will result in a positive expectancy if taken over time. It shows up on his favorite stock and he takes it. It ends up as a losing trade. The next week it shows up again, he takes it and again it ends up as a losing trade. At this point the trader gets frustrated and decides that the setup doesn't work, he discards it and continues his search for the next Holy Grail. This trader has failed to understand the probability game. To quote the text above, "He is desperately trying to create certainty where it just doesn't exist".

Another possible outcome is that he is so confident and sure that his trade will work out that he refuses to cut his losses even when his predefined stop loss level has been triggered. Similarly, he has failed to understand the probability game, failed to realize that even a 90% hit rate system has a 10% chance of failure.

I can use my previous posts as examples too. Refer to my recent GBPUSD trade and DOW analysis posts. I was really confident with the setups on both charts but they both ended up as losers (Thankfully I did not make any new US trade). Am I supposed to conclude that my setups don't work and discard them? No! I simply accept that no setup is 100% accurate and remind myself of the fact that if I take them over time, my edge will play out and I'll end up profitable. This is so so important but yet so hard to grasp. Mark Douglas also wrote (not shown above) that it is an inbuilt human trait to want to be right all the time, and that thinking in terms of probabilities is not natural to us, it requires a conscious effort. I mean search yourself, have you really internalized the fact that trading is a probability game? It is definitely not easy, and I for one know that I've not yet attained. I guess we can only be certain that we've understood when we no longer feel a tinge of pain or a shred of doubt when we make losses, even if it is a string of losses in a row.

It is hard to bring justice to the profound wisdom and eye popping revelations in the book, I really suggest that everyone read it as it is one book that will definitely take anyone's trading to the next level. Heck it is not the most popular trading psychology book for nothing...