When trying to educate the class-warfare crowd, the main challenge is helping them understand that the economy is not a fixed pie.

More specifically, I try to show them that it’s possible for all groups in society to become richer. And I usually also try to help them realize that the policies that help some people get richer almost always are the policies that help everyone get richer.

In other words, President Kennedy was right that a rising tide lifts all boats.

That’s true in America and true around the world.

Today, we’re going to deal with a different type of class-warfare argument. Earlier this year, Carol Ryan wrote a column for the Wall Street Journal that fretted about billionaires.

But instead of complaining that rich people were enjoying too big a share of the gains, she hypothesized that billionaires are actually bad for prosperity.

I’m not kidding. Here are some excerpts.

…a look at who picks up the tab when billionaires scrimp on taxes, and how wealth concentration is affecting the wider economy, shows why the..risk is that the U.S. economy becomes increasingly dependent on a narrow group of very rich households, whose spending is tied to the performance of the stock market. This could mean the entire economy pays a steep price in the next market correction. …The top fifth of wealthiest households now account for nearly 60% of personal outlays, up from 50% in the early 1990s, data from Moody’s shows.

Ms. Ryan is basically making a Keynesian argument that consumer spending drives the economy.

Based on this theory, a drop in the stock market, known as a correction, will cause rich people to spend less. And since rich people do a lot of spending, that will be harmful to growth.

But the problem with argument is that Keynesian economics is backward. Consumer spending doesn’t drive the economy. It’s just the opposite. The economy drives consumer spending.

I also think the article is a bit disingenuous in that most of the column focuses on billionaires and how they supposedly are not taxed enough, yet when Ms. Ryan makes her Keynesian argument, she suddenly cites the spending of the top-20 percent.

At the risk of understatement, that’s a very dodgy switch. There are tens of millions of people in the top 20 percent in America, compared to about 1,135 billionaires.

Incidentally, the column includes this chart, which actually undermines the class-warfare argument. As you can see, the top-.01 percent have become wealthier, but so have all the other groups.

P.S. I can’t resist making one final comment. Ms. Ryan’s column includes discussion of the proposed wealth tax in California. Here’s a sentence that caught my attention.

Federal cuts to the state’s Medicaid program will leave its health system short of billions of dollars.

And why did I notice this sentence? Because it is absurdly dishonest/inaccurate. As I wrote a few days ago, Medicaid spending is skyrocketing, both nationally and in California. Our friends on the left shouldn’t assert a budget is being “cut” merely because it isn’t growing as fast as they would prefer.