>because we'll keep running out of other people's money.

that doesn't make a whole lot of sense, for two reasons. For one, as even Paul points out in the piece, a wealth tax below what's practically a risk free return on capital (~5%) doesn't eat into the capital stock, it simply means wealth grows slower, but still increases.

Secondly, there's no monotonous historical direction towards higher wealth taxes, in fact the opposite. We're living in an age of low wealth taxation, with only half a dozen countries or so, if I'm not mistaken, imposing one at all.

The risk free rate of return is usually only a point or two above inflation, and I’d argue that real wealth, rather than nominal wealth, is the true measure to look at to determine whether someone’s position has improved, stayed flat, or decreased.

> it simply means wealth grows slower, but still increases

But what does this mean? If you have a load of money in some companies, that's helping to fund their activities, and the companies' share price goes up a bit, you haven't gained any money. And you won't gain any until you sell some shares, which is already taxed.