Ive seen this kind of sentiment around (referring primarily to your initial comment on the OP about making a new foundation, but replying to this one because I wanted to have the context it adds with it). Its a sentiment that sounds appealing ("this thing is hurting us, therefore me must destroy it/replace it" is a fairly cathartic notion after all). The problem I have with it is: the analogy doesn't actually fit. Government and economic systems simply aren't buildings. They dont have foundations in that sense, and the things metaphorically referred to as "foundations" do not have the same function and consequences as the real thing.

Take your examples. If you were to remove racism from the country overnight, say you somehow both make individual bigoted people all understand that their perceived enemies are people just living their lives, and adjusted the outcomes of various systems to remove systemic racist outcomes that can exist even without personal malice- that wouldn't suddenly cause the government to collapse. It'd probably change who exactly gets elected and some of the laws for the better, but while racism has shaped the history of the United States, it doesn't logically require racism continue to shape it in order to prevent calamity of some kind.

Settler colonialism has a stronger claim to being "foundational" in that the concept describes the process by which the country came to be- but there we have a different problem when one contemplates the consequences of removing it: it simply can't be removed. Not because of some negative consequence, but simply became there is no way to undo what it results in. Numerous people were killed, and they and their would-have-been descendants cant be simply brought back. Hundreds of millions of people that have an entirely different culture to what would have been now exist, some of those cultures unique to the area despite not being indigenous to it, and it would be logistically impossible to send them anywhere else. The surviving indigenous people can be given some kind of reparation, and the poverty forced on them can be alleviated, but realistically it cant be nearly proportionate to what those groups lost. Unless one has a time machine somehow, whatever the US becomes, even if it was entirely destroyed and built anew, it can never be a society that doesn't owe it's existence to a settler colonial enterprise, any more than one can change who ones parents were.

This isn't an argument against radical change, and I know its rant-y and pedantic, but I see the sentiment of "tear it all down" so often, and think that's just too vague. It sounds dramatic and radical, but leaves the question of what it means too open. Does it mean "replace all the major government figures"? Probably not, that happens anyway given enough time, without radical changes necessarily occuring. Does it mean doing that, but also changing the mechanism by which those leaders are picked, and maybe also something like the economic model or ownership structure of various institutions? Maybe, though still, apart from the people at the top, a lot of what you'll get will still be the same. You're going to need bureaucrats and lawyers and teachers and auditors and soldiers and whatever, or some broadly equivalent roles, no matter how you organize your society, and since the people doing that now are the ones that know how, they'll probably end up doing the same things under the new order (which could make some cultural problems, like racism for instance, very hard to root out. A biased teacher isn't going to stop being biased just cause you changed their boss and the laws, for example). Maybe you conclude that that's not enough, and that one has to change all the laws and ownership structures and bar everyone that participated in administering the old system, even on a local level, from an equivalent role in the new. But that has a rather disastrous history; you end up with a huge number of new and not yet competent civil servants, and a class of people that cannot easily make a living because they are barred from using the skills they actually have, that can turn to crime or reactionary militant groups.

This probably comes off as ranting at you in particular, I'm sorry about that, I just can't reply to an entire general sentiment as that's not how the platform works, and I'm sure Im guilty of saying these things too. But I feel like too many calls to action don't really specify what specific action they call for, just analogies and notions of "there's something about our society that's hurting us, we must destroy", or "we need to do something about [monolithic problem], or "organize" (which sounds like a specific action, except half the time people say it they dont really specify who with or how to do it effectively or what the organization should do once formed, and it's not realistic to assume those things come naturally to the inexperienced), and I feel like they'd make for more effective tools of political discourse if they did advocate for unambiguous courses of action rather than just the vague result one wants that action to achieve.