It seems like everyone is talking about the wealth tax. Many Democratic presidential hopefuls have endorsed it as a way to address income-inequality concerns. There is also the promise that it would raise much money from the richest Americans and pay for all the new entitlements Democrats think Americans lack. However, a careful examination of the evidence reveals that such a tax is unlikely to achieve any of these goals. It is also misguided, as the negative consequences from the tax will reach far beyond the richest Americans. 

Consider the version of a wealth tax proposed by Elizabeth Warren. She was …