Trading and Gambling while having some similar elements are NOT the same at all. Thus any reference to games of chance and trading using the odds commonly found in gambling are irrelevant and I'll explain why.
Odds are nothing to be concerned about, there are odds for everything in life. It's simply a way of understanding and categorizing the space of possible events.
Example:
Right now, sitting at your computer, there's a possibility that a voltage spike could destroy your hard drive. There's a possibility that your hard drive could fail for mechanical reasons. There's a possibility that you could accidentally delete a lot of data. There's a possibility that a virus could delete it for you. There are some odds that you could lose everything on your computer, but that doesn't stop you from using it or putting things on the hard drive. Instead, you manage that risk by backing up, or choosing not to manage it at all.
In Black Jack when you recieve two 10's or cards of the same value, while you can add to your risk, you cannot take 1/2 your bet off the table in profit and use the house's money to continue playing. Likewise if you bet on a football game or a fight, you cannot scale out of your bet when the score goes in your favor. That difference is huge. Trading allows you to "protect" your position at any time the trade goes in your favor, and this increases the odds that you will NOT lose.
All of that then boils down to trade management, which boils down to taking new trades that manage your open position. It's a way of expressing a belief about the market in the form of an open position. As price goes in your direction, if you become less certain about it's sentiment then you should certainly close some of your trade. However, doing so randomly makes no sense (just as random entries make no sense), which means you need to express some edge when managing trades.
Finally, in gambling, you must CHOSE to continue losing. Each game represents one chance and has a finite outcome...your bet. If you want to continue losing you must take action and place another bet. However in trading (for those who chose NOT to use a set stop loss) you do not have to do anything to continue losing. In fact you must take action to STOP losing by closing out your trade. That is why placing a stop loss on any trade improves your chances of winning.
However I stand by the theorem as stated...trading styles and spreads, etc. do NOT negate or change the basic facts of trading. The only thing they change is how often that trade will land heads or tails, BUT IF you chose your direction wisely, place a reasonable stop, and time the entry well, the odds of having a winner are in your favor. Which brings me to my final point.
Obviously nobody will argue with the premise "if you choose a direction wisely, the odds are in your favor" since it's true by definition.
But that's independant of either stop loss or entry timing. Add in entry timing and things get harder, but it means you can use leverage so your gains are better too. Add in stop losses and your odds actually go down, but your risk goes down too, thus your net volatility improves.
