I think the real problem lies in the ratio of compensation to productivity. The ratio depends, obviously, on how productivity is measured. When this ratio gets out of kilter a serious threat to societal stability arises. Human nature is such that the ratio, will spontaneously move from a reasonable balance across society to an imbalance, unless some external force is imposed to keep the balance, or to bring the ratio back into balance. The most important force tending to keep the ratio in balance is free, unfettered competition. Because of human nature, Monopolies, Cartels, and capitalism (please see the dictionary definition) provide a counter force that tends to unbalance the ratio. In the the US, as in some other nations, the ratio is becoming unbalanced. A sufficient imbalance can result in societal chaos or revolution. The British satirist and amateur philosopher, Malcolm Mugggeridge, gave perhaps the most succinct summary of Human Nature when he said: All human endeavors can be attributed to Vanity, Greed, or Instinct.
If the rich were stuffing the money under their matresses, it might be a good argument, but they're investing it. Even if they're making a completely stupid investment, the money isn't disappearing. Someone is on the other side of the trade. The money is circulating. I should add, reading the whole article, it does make a good case against a VAT. Although in a very roundabout way.
but by their very nature the rich will "invest" if for example housing rises 50% a year they will go all in on housing. Why? The yield-chasing. Rich chase yield, unlike the plebs who are dumb and just consume. But yield-chasing is not always a good thing you must understand.