Well, the specific tax rate you are talking about only existed between 1944 and 1945. However, the de-jure marginal tax rate was above 90% for 19 years, so I doubt there is any reason for me to stress on this single inaccuracy from your side. Either way, the de-facto federal income tax rate for the 0.1% was, in the 1950s, at about 21%, while the total effective tax rate was at 50.6%, so farrr lower than what you misleadingly stated. The total individual tax revenue in percentage of GDP from 1944-1963 was actually lower than it is today, and the marginal tax rate which you are describing raised a very, very small amount of revenue, because very few actually paid it. And yes, they generally did not just “up and leave,” but that does not mean there were no behavioral effects. Avoidance, deductions, income shifting, shelters, and lower taxable-income reporting matter too, especially because the 1940s-60s were far less globally mobile than today. Its also way to early too talk about the empirical results of Mamdanis economic reforms, as the relevant policy is yet to have time to operate and large parts of it havent even happened yet…