Marcel Link in his excellent High Probability Trading is not the first to equate the skills of the professional gambler with the skills needed to succeed as a trader but he does it very convincingly:

[The professional gamblers] don’t take unnecessary risks or gambles. They know when the odds are in their favor and will bet more when the odds get better. If the odds aren’t there, they won’t risk nearly as much, if anything. They know how to protect their winnings, and they know how to call it a day when Lady Luck is blowing on some other guy’s dice. Having this discipline lets them come back to the table the next day. […]

They know that losing is part of being successful, and as long as they do the right things, they are okay with losing; they won’t try to make it all back on the next hand. They know that if they stick to their rules, they will make it back in the future by being consistent. […]

Successful gamblers also know they don’t have to be in every hand. A good poker player is disciplined enough to fold hand after hand until the right one comes along. […] For the most part it’s the amateurs who try to bluff. Pros do not do it nearly as much; they would rather go for the sure hands and sit out the rest. […]

[The professional gambler] doesn’t necessarily increase the size of his bets because he is on a good streak or has doubled his money. Very rarely does a pro make bigger bets because he has a hunch or feels invincible