So what is stopping it from happening?
Lack of political will.
https://www.theguardian.com/news/article/2024/jun/25/international-scheme-to-tax-billionaires-wealth-technically-feasible-study-finds
"International scheme to tax billionaires’ wealth technically feasible, study finds"
Because political parties don't like funding being cut off and taxing their billionaire friends might offend them.
Fuck that.
TAX THE RICH!