It had been tried in many places already: Chile, Indonesia, the Philippines, and (before 1979) Iran. The data were clear: it had worked very well for capitalists, but very poorly for people in the countries affected. And it mostly has come to the US. There are remnants of the welfare state, but your employer can basically do whatever he wants because he calls himself "a job creator"... and education is debt-financed... and getting sick will wipe out everything you have... and we've transitioned away from productive investment to asset bubbles... and you better not end up in a lawsuit because the rich have the best lawyers and lobbyists and therefore effectively own the court system (you only have a shot if you can find a rich person who hates your adversary enough to back you). The EU has held out to an extent, for now, but it won't if the Davos people get their way. The "Great Reset" is their plan to implement extreme capitalism under a guise of ecological caution and "woke" multiculturalism [1].
The Marshall Plan was written by people who believed market systems were superior to central planning given the technological level and geographical complexities (e.g., general low trust between nations) of the time--they were capitalists, but not capitalist ideologues. Alas, the successes (for "business interests", meaning rich people in the US) in Santiago, Jakarta, and Manila led them to become more brazen, to the point of using the former USSR for some of their most aggressive experiments to that point.
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[1] This is not to say ecological caution isn't important (it is). Nor is it to disparage the broader set of social movements classified by their detractors as "woke", most of which have nothing but the best intentions. The issue with "woke capitalism" is that it retrenches in identity politics in order to divide working people against each other for Capital's benefit, and that it is designed not to provide significant help to people in marginalized groups (most of whom are working class, and who will therefore not be helped) but to neuter a powerful, morally righteous leftist movement toward genuine and universal social justice.
To me it seems like they have the best intentions in the same way that religious extremists have the best intentions. But otherwise I agree with you.
Some ultra-capitalist die-hards have even retreated away from Liberalism in general as they found it too restrictive for their extreme ideology (they know their economic regime could never gain sustained popular support; it would need to be imposed)