I wrote this a few years ago in response to a similar piece: The problem is that the rich have the ability to take their income in alot of different ways. Tax income more, they'll take it as dividends. Tax dividends more, they'll take it as capital gains. Tax capital gains, they won't realize their capital gains until they can offset them with realized losses or they'll just get bank loans again't their stock holding…
You could tax holdings in the US or by US citizens instead of earnings, then. Make it expensive to hold capital. Capital in motion and at a high velocity is generally good for everyone. Capital at rest serves very few and is very harmful to everyone else.
This is dangerously wrong. No economist would tell you that a high velocity of money is an inherent good, or even that increasing the velocity of money is an unfettered good.
Public infrastructure, mortgages, venture capital, small business loans - all of these are investments, and making it more expensive to hold capital will dry up access to money for these sorts of projects.