It's a step, but trying to limit how money itself is spent will always create loopholes your opponent has better lawyers than you to exploit. Imho the better way to discipline billionaires would be to change tax code such that borrowing money against securities or anything like it (such as stock) is counted as realizing their value, which would trigger capital gains tax obligations.
It'd have somewhat similar effects to a wealth tax with way less administrative load for the state. The only exception I would grant is when you're buying a single-person/single-family residential property you're going to be living in yourself.