Medical doctors are notorious for bungling their financial decisions.

First, they always start in a hole. They've usually got a six-figure pile of student debt. And they don't start earning much money until their early 30s.

Worse, doctors are overconfident. They've spent years in school honing their specialty in medicine. They think good grades and paper intelligence in the medical field translate to success in finance. They don't.

That's what happened with an attending physician I trained under. I like to call him "Dr. Internet."

Dr. Internet made a particular kind of investing mistake. And unfortunately, it led him to financial ruin. Let me show you how it happened, and how you can avoid making the same destructive mistake today...

Once he found out I had previously worked on Wall Street, Dr. Internet pulled me into his office almost daily. "I've been doing pretty well in the market," he told me.

He talked about his positions in technology companies that are still around, like Oracle (ORCL) and Qualcomm (QCOM)... as well as a number of long-gone Internet stocks.

The year was 2000... right before the big tech-stock bust.

He mentioned large dollar figures. Instead of teaching me about medicine – what I was there to learn – he was trying to convince me how smart he was with stock investing.

He had way too much money in these overhyped tech stocks. And he wasn't worried. That's usually the sign of a market top. When your dentist, your plumber, and the intern working in your office have hot stock tips for you... it's time to sell your stocks.

I tried to tell Dr. Internet that he was being reckless. I told him that these stocks could rise, but the economics didn't make sense. He also needed to consider that they could fall. The companies had no cash flows and no profit margins. They weren't making money yet...

He didn't listen. The Internet bubble collapsed. And this smart, successful doctor filed for bankruptcy. He lost his house and his wife.

Dr. Internet's mistake wasn't that he invested in tech stocks during a bubble. He was guilty of a far more common error... a blunder that you may be making right now.

His mistake was that he didn't have a plan. He had only one way to win. Tech stocks had to keep going up and not go down. If anything else happened, he'd go bust.

That's a narrow path to success. It leaves you no room to maneuver.

You should invest to boost your wealth over the long run. And you can't expect to spot every boom and avoid every crash. Even professionals can't do that.

A Yiddish proverb cautions, "Man plans, and God laughs." The real world is a complex and unpredictable place. If you draw a specific timeline for how you expect things to go, the world will almost certainly prove you wrong.

Did any of your investment plans three years ago include a British exit from the European Union or a potential President Donald Trump?

You don't know what's coming around the corner. I don't either. And that's the key. Armed with a balanced portfolio, you don't have to worry about the future.

Had the doctor stuck to his work as a medical teacher... invested the bulk of his portfolio in safe, blue-chip companies or low-cost index funds... and only used a few thousand here and there to speculate on the trendy Internet stocks... he'd have had all the fun of gambling, the bragging rights, and even plenty of money to roll into other investment ideas as his fortune grew.

His life wouldn't have been destroyed. But instead, he only gave himself a narrow path to victory.

Take a close look at your financial picture. Is the majority of your portfolio relying on a big prediction of the future? That's a warning sign. Major predictions shouldn't be necessary for your wealth to grow...

That's why I urge you to review your entire portfolio before the new year. Figure out how it can stand up to these uncertain times. If you only have one way to win, you need to make some adjustments immediately.

Over the long term, the stock market is the greatest wealth-creation tool at your disposal. It's likely the market will go on to hit new all-time highs. And you want to be sure that the stocks you hold will take you and your retirement wealth to new highs too.

With a little bit of planning and knowledge about the businesses you own, you might also get to laugh with God.

Here's to our health, wealth, and a great retirement,

Dr. David Eifrig

Editor's note: Doc has found the perfect way to broaden your path to victory as an investor. This little-known technique can help you collect regular payments three to five times higher than what most folks get from Social Security... And the best part is, you can do it in about 15 minutes a month. Click here for more details.

Having just one path to success in investing is dangerous. So you want to take advantage of the upside in stocks, while giving yourself more ways to win...

Market Notes

THIS MEDICAL-DEVICES COMPANY IS RIDING THE HEALTH CARE BULL MARKET

Today's chart shows the long-term uptrend of a niche medical supplier...

Doc has been bullish on health care stocks for years. As he sees it, the surge of aging Baby Boomers in the U.S. means more patients will need checkups, prescriptions, and diagnostics tests. This flow of money into the industry is good news for companies that supply health care providers...

For example, let's look at Atrion (ATRI). The billion-dollar company makes medical devices for highly specific markets – supplying crucial items like cardiovascular, ophthalmic, and fluid-delivery products. From surgical loops used in minimally invasive procedures to valves used in life vests, Atrion makes up for its small size by supplying niche devices... And it's clearly paying off. The company increased profits in the recent quarter by 16% year over year.

And as you can see, Atrion's stock is in a strong uptrend. Shares have more than doubled over the past four years, recently hitting a new all-time high. Doc's bullish call on health care continues to be a safe bet over the long term...