Dennis Bergkamp

Article from the Guardian.

Then Wenger gives the example of a player who knows he ought to pass but takes a massive gamble and scores. "If he really loves the game he'll go home and worry about it. He'll know he really should have passed to set up an easy chance for someone else. But he was selfish and got lucky. If he doesn't care about the game he'll go home and think: 'That was great – I'll do the same next time.''

Same for following your rules in trading. Don't be fooled by randomness.