Sen. Elizabeth Warren says she wants “billionaires to stop being freeloaders.” It’s a statement akin to the idea that billionaires need to “give back” to society. Which is not how I immediately think about the wealth inequality issue. Surely Microsoft co-founder Bill Gates didn’t begin to “give back” or generate value for society only when he began “giving back” via the Gates Foundation to boost education and reduce global poverty. Society benefited from his role in revolutionizing home computing, generating massive wealth for retirement plans everywhere, and creating hundreds of thousands of jobs over the decades.

Oh, and Gates became superrich in the process. And he should pay taxes. Lots of them. Does he or other wealthy Americans pay anywhere near enough? Warren and many Democrats don’t seem to think so, (although paying for new spending does seem to be the primary concern here). Thus the talk of a wealth tax or a higher top income tax rate. There’s less talk on the left, however, of possible tradeoffs from such ideas. A wealth tax would certainly be a theoretically powerful — though difficult to administer and possibly unconstitutional — way to break up or diminish concentrated wealth. (Many nations that have tried them have since abandoned them.) But there is another side of the story. My AEI colleague Alan Viard notes that wealth taxes of the sort Warren advocates “would be a drain on the pool of American savings, [which] finance the business investment that in turn drives future growth of the economy and living standards of workers.” Something to consider at a time when the American economy faces historically low economic growth due to demographics and low productivity.