Your emotional reaction to gains and losses doesn't tempt fate. You tempt fate by subjecting yourself to more risk than you can manage/tolerate.The simple fact is that you tempt fate by either being overly positive or negative about gains or losses.
People brag because they're either bullshit artists or they're looking for approval. People increase their size because they're either too stupid to know better or they know what they're doing and can manage the risk.Bragging about gains brings upon you an overly confident attitude that nothing can touch you. You start to increase your size, increase your use of margin. The market seems to be with you for a while until it comes crashing down and fate bites you where it hurts most.
Discipline involves using your intellectual abilities to control your emotional disabilities.

