I've overheard people complain that they lost money because Alan Greenspan raised, lowered and/or left rates unchanged. Oh, and Eliot Spitzer, too.

Well, folks, I've got some bad news for you. None of those are the reason any of you lost money. The dirty little secret is much simpler. You lost money because you bought a stock, and that stock went down, and then you sold it. Period, end of discussion.

Buying high and selling low is a lousy investment strategy. Worse is buying high and not selling at all as (paper) losses mount. Think of Lucent (now Alcatel-Lucent ( ALU)) or Sun Microsystems ( JAVA) or Nortel ( NT), or the slew of stocks that went to zero. Too many people rode 'em all the way down, rather than admit a mistake and take responsibility.

You see, with responsibility comes a natural tendency toward planning. If you buy without a plan in place for when things go south --- when your original thesis turns out to be wrong -- then you are at fault.

Sorry to be the bearer of this bad news, but the sooner you start accepting that simple truth, the better off you will be.

Why? Because all of the excuses above are foreseeable events that only investors (and fools) fail to anticipate. Analysts can be wrong, TV is about ratings, insiders sell, and talking heads talk. Is that a surprise? Hey, guess what? The Fed raises and lowers rates, the FDA pulls drugs, and attorneys general prosecute.

Review some of the aforementioned complaints, and you will see how foolish they sound. Now try this one: I lost money because I made a bad investment. I lost a lot of money because I made a bad investment without a contingency plan for when things went wrong.

If you liked this article you might like

Ritholtz: Boycott Overstock.com

Ritholtz: Boycott Overstock.com

Ritholtz: Ten Bullish Charts, Signals and Indicators

Ritholtz: Ten Bullish Charts, Signals and Indicators

RealMoney Extra: Be Cautious With Builders

RealMoney Extra: Be Cautious With Builders

15 Ways to Check Data

15 Ways to Check Data

What Investors Need to Know About Historical Data

What Investors Need to Know About Historical Data