Listen to the excuses a person makes after an underwhelming outcome, and usually you will find the same group of reasons cropping up: either the market wasn't behaving rationally (investing), the other team played dirty (sport), the contract was awarded to the highest bribe (business), the economy is bad (business again), or the other person was unwilling to change (relationships).
It's one of the most difficult things on earth to be introspective and objective about your shortcomings fresh on the heels of a failure. A society that's only interested in results and nothing else doesn't encourage you to be candid about your errors either. However while pointing a finger outward may shirk responsibility and can even be therapeutic, it will not bring any progress. Excuses like the list above are now so common to the point that they have become worn out cliches. Worse yet is that they are generally acknowledged as logical, valid reasons: they make perfect sense at a conversational level.
Dangerously these excuses start blinding you to the truth. This blindness and denial - rather than some isolated failure - turns people into losers over time, because without truthful introspection one can never improve. When you blame an external situation you don't analyze your own actions further, hence no personal advancement. You can't improve if you refuse to acknowledge what you did wrong.
With time and repetition these excuses become self-fulfilling prophecies, ever more powerful each time. And with an excuse-based mindset you will continue to think and perform at the same level you always did. After a few attempts you will become disenchanted, convinced that Lady Luck doesn't favor you and eventually quit, when the hard truth was you didn't step your game up or change your angle of approach where necessary.
If you probe a generalized excuse you will usually find it to be baseless. A generalized circumstance either doesn't apply or has negligible impact on you if it does. The fact is most factors are within your control most of the time. Worded differently, you could say that the factors which matter most are in your hands. Uncontrollable issues like market sentiment, government policy or the weather could set you back, but they never mark the closing chapter.
You can adjust your sails to a change in wind direction and still get to your desired destination. If the stock market is volatile, stay out the market or hedge your risk by investing in an alternate sector and employing a stop-loss strategy. If the other sporting team plays dirty and gets away with it you should question why you're even competing in such a league or sport and shift to one where the playing field is level. There's always a choice and you must never allow circumstances to dictate and dominate.
Forget all excuses. Once in a blue moon they actually are valid, but from a psychological and personal performance standpoint they don't help. Accept full liability for all results and calmly proceed to break down what you did in an objective post-mortem. If you take things very personally then imagine you're critiquing someone else - you're more objective when you're less self-conscious.
After any disappointment identify what you need to do differently next time, implement it then analyse the result again. Keep repeating this loop until the results become favorable. Believe and behave as if the result is fully in your hands, and that too will become a self-fulfilling prophecy.