If they did tax the wealthy heavily, they’d probably leave the country, and pull their money and resources with them.

We did tax the wealthy heavily- in the period between FDR and Reagan. From the 40s to the 80s the top marginal income tax rate was between 70 and 94%. And do you know what the ultra-rich did? They prospered along with everybody else, they stayed put in the USA, and they seethed about other people prospering and their loss of power and influence.

You know what else they did? They spent money to corrupt politics, to pack the judiciary, to legalize bribery and money in politics, to build international legal frameworks to prevent countries from regulating or taxing their billionaires. They stood up propaganda organs to subvert democracy, they paid politicians to betray the voters and strip away their labor protections, and here we are today deep into the garters of another gilded age.