"Whatever money you may need for the next five years, please take it out of the stock market right now, this week. I do not believe that you should risk those assets in the stock market right now."
-- Jim Cramer, Today Show, Oct. 6, 2008; S&P 500 at 1,056.89.

Six months ago, and thanks in no small part to the statement above, I concluded that Jim Cramer was a menace to investors.

It took only a few months for the rest of the nation to catch on. Jon Stewart finally jumped on the bandwagon earlier this month and exposed the man for what I think he really is: an entertaining (if not irritating) media personality, but certainly not the champion of the individual shareholder that he often claims to be.

In fact, I consider him to be the closest thing to a walking, talking hazard for the individual investor there is. Now, Jon Stewart may have the jokes, but I have the real reasons why Cramer is precisely that -- a hazard to investors -- and why you should take a pass on any investment advice he tries to give you.

Thank you, Jon Stewart!
I continue to fully applaud Cramer's stated goal -- to help people make money by investing in the stock market. But Cramer's outburst six months ago was a mistake -- plain and simple. And, as Stewart so kindly illustrated, it wasn't his first time.

You see, when someone issues panic-inducing market calls, as Cramer does from time to time -- and urges investors to avoid long-term strategies to buy and hold good companies -- the average investor simply gets crushed.

Cramer's Today show plea was grounded in a sound reality -- Fools should never have money they need during the next five years in the market. But by advising people to indiscriminately sell, he helps contribute to exactly the thing that he's trying to avoid: losing money.

Chances are, most viewers were petrified even before Cramer spoke -- the market's been up and down (and mostly down) more times than a yo-yo lately. Even a very small push these days is likely to persuade investors to join the terrified herds pulling their money out of the market.

And nearly six months later, Cramer appears to be the next Oracle at Delphi as we sit in a market priced well below his initial call. Though I'm happy for those who were able to pull themselves out -- and many did -- it's a disturbing trend to witness.

Between October and the end of November, investors pulled out a whopping $140 billion from U.S. equity funds. Based on what these funds were holding, they were indirectly pulling out of mutual fund mainstays such as Waste Management (NYSE:WMI), 3M (NYSE:MMM), Yum! Brands (NYSE:YUM), Yahoo! (NASDAQ:YHOO), Texas Instruments (NYSE:TXN), and Caterpillar (NYSE:CAT) -- many of which had already been hammered.

Cramer might've saved people some money in the short term -- and I'm pleased for that. But to complete the circle, he'd have to tell these people precisely when to get back in. I'm not sure how loudly I heard him yelling on March 6 when we reached that recent market low.

And instead of holding onto the steady blue-chip stocks that have historically provided investors with some of the strongest long-term returns, many investors have been progressively selling at historic lows ... thereby ignoring the sound and sage advice from names such as Buffett, Lynch, Graham, Munger, and Bogle. That's the larger point.

You don't need a weather reporter ...
I'll admit that Cramer is entertaining, but no one can consistently forecast the direction of the market as he pretends to be able to do. I repeat: No one can consistently forecast the direction of the market.

It moves completely randomly and unpredictably over the short term -- and therefore trying to make a "call" on the market won't consistently work out for you. Pick a direction (up or down), and there's a 50% chance of being right -- even though the prediction is rather meaningless.

It's like Punxsutawney Phil. The furry little critter climbs out of his hole and either sees his shadow or he doesn't. Whichever it is, the result has nothing to do with whether winter is over -- just like a stock market prediction has nothing to do with the market's movements.

The scary part is that Cramer has flip-flopped numerous times. He's called the bottom already several times in recent months. While CNBC may gloss over this fact, I've taken careful notice. Don't forget about his theory that 2008 would be the year of natural gas. Ouch.

The talking heads on TV get paid to put on a song-and-dance show and attract viewers. Your education or your personal success, as Jon Stewart kindly brought to light, is a secondary priority -- or not a consideration at all.

Whether Cramer turns out to be right or wrong in the end just isn't the point. The point is that no one can claim to predict the markets -- no one. If you follow the advice of those who say they can, it's likely to cost you thousands, if not more.

Here's the real problem
In the real world, there are commission costs, taxes, and opportunity costs -- all of which have a tremendous impact on the returns that you're likely to experience.

Every time you pull the trigger in your account, think about your broker and the tax collector doing a little touchdown dance. Much of their income is predicated on your transacting as much as possible.

Take a hint from someone who knows a lot about the hidden costs of investing: John Bogle, the founder of Vanguard Investments. He writes: "No matter how efficient or inefficient markets may be, the returns earned by investors as a group must fall short of the market returns by precisely the amount of the aggregate costs they incur. It is the central fact of investing."

Think about that the next time you hear "Buy, Buy, Buy" or "Sell, Sell, Sell."

And for those who listened to Cramer on his recent market call, don't forget that he has quite a monumental task in front of him: He has to precisely tell you when to get back in.

The Foolish bottom line
If you want to make money in the stock market, you need to tune out the panic -- or the euphoria. You need to remember that no one has any idea where the market is going in the near or medium term. You need to buy shares of great, built-to-last businesses. You need to hold for the long term. And you need to keep as much money as you can from the tax collector or your broker.

That's what we do at Motley Fool Stock Advisor, and it's paying off. Take two of our best stocks, Marvel Entertainment and GameStop (NYSE:GME). We recommended buying shares of these stocks six and five years ago, respectively. Both have absolutely thrashed the market by incredible margins.

What was the cost of doing all of this? Probably $24 in broker fees and $0 in taxes. That's a perfect example of what I'm talking about. In fact, our whole scorecard is beating the S&P 500 by 34 percentage points.

As for Cramer ... he undoubtedly has an uncanny knowledge of tickers, prices, and strange catch-phrases. But what he sorely lacks -- and what you must never forget in your investing days -- is temperament. It was Warren Buffett who once said that "the most important quality for an investor is temperament, not intellect."

Want to see what else we've recommended and what we're recommending now? Click here to get a free, 30-day trial to Stock Advisor -- there's no obligation to subscribe.

This article was originally published on Oct. 23, 2008. It has been updated.

Nick Kapur owns shares of Marvel Entertainment. Waste Management is a Motley Fool Income Investor recommendation. 3M and Waste Management are Inside Value picks. The Motley Fool's disclosure policy would never suggest that it could predict or time the market.