I drove by Mar-a-Lago yesterday afternoon. It's Donald Trump's beautiful 20-acre oceanside estate in Palm Beach, Florida. You can't miss it. It's the only mansion on wealthy Ocean Boulevard with a huge American flag flying from an 80-foot tall flagpole in its front yard. It stands as Donald Trump's public declaration that rich people can be just as tacky as poor ones.

It's not clear to me why anyone ever thought a publicity-seeking blowhard like Trump would make a good president, yet Republicans have flirted with the grandstanding real estate mogul for years, and even embraced him for questioning the authenticity of President Obama's birth certificate.

It was just a few months ago when Trump proclaimed the Obama economy "a disaster." Before that, he argued that Obamacare was costing U.S. jobs and complained Obama wasn't "fixing the gasoline situation." I wonder what he thinks about official numbers released this morning showing the economy has added 12 million jobs in the five years since the Affordable Care Act was passed or about the lower gas prices that have saved American drivers more than $100 a month.

Donald Trump is a prime time example of why rich people don't necessarily have any special knowledge about the economy. Trump may be an expert when it comes to commercial real estate or self-promoting TV shows, but I'd trust an unknown junior college macroeconomics professor before I'd listen to The Donald on how to run our national economy.

The time and energy it takes to develop a Trump-sized fortune often requires years of single-minded focus and dedication that may not allow you to see the broader picture outside your particular field. And when you live at the top of a bubble where your colleagues defer to the wisdom of your success, you start to believe your own hype.

The 2012 presidential election should have taught us that successful businessmen like Mitt Romney and Herman Cain don't always have a clue about how to fix a broken economy. But now the run-up to the 2016 election is also reminding us that prominent doctors don't necessarily know anything about public health.

A few weeks ago, Senator Rand Paul, a top GOP presidential contender, made the irresponsible claim that measles vaccinations cause "profound mental disorders." Of course, the Kentucky Republican should know better, but Dr. Paul's claim is worse coming from a licensed ophthalmologist, who should also know that measles is a leading causes of child blindness.

Which brings us to Dr. Ben Carson, a world-renowned brain surgeon who ranks among the top of the GOP's crowded list of 2016 presidential hopefuls. Think of Ben Carson as Herman Cain with a stethoscope. Like Cain, Carson is a prominent African-American who has earned public acclaim for his success in his field. And like Cain, Carson has made outlandish comments that suggest a profound ignorance of public policy matters outside of his field.

This week, Dr. Carson was forced to apologize for his irresponsible and uninformed statement that homosexuality is a choice because "a lot of people who go into prison go into prison straight — and when they come out, they're gay."

The scientific community disagrees, as CNN and numerous others reported this week. They point to decades of research showing homosexuality is not a choice. "Sexual orientation is biologically determined," said one psychology professor. "I don't think any educated person aware of the research would argue differently."

But who cares about research and scientific consensus when you're a famous doctor with a half-assed opinion? Carson also believes homosexuality is comparable to bestiality, evolution is a myth, the Keystone pipeline is "perfectly safe" and Obamacare is "the worst thing that has happened in this nation since slavery."

When are we going to learn that famous people who are successful in one field aren't automatically experts in everything else? Sometimes they don't even know about their own field beyond their speciality. Business executives don't always know about the economy. Doctors don't always know about public health. And even brain surgeons can be idiots. You don't have to be a rocket scientist to see that.

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