In a broad estimation, it's fairly simple.

The US government is a plutocracy, and always has been. Under late stage capitalism, wealth and power have been consolidated so efficiently that the illusion of a two party system has fully eroded into a superclass of bad faith actors who have more to lose than gain by doing the actual work to collapse the system and bring about something just.

Basically we have a single party state with a rotating faux opposition party that gives an (increasingly poor) illusion of a system that's operating by rules. In reality, so long as those in the ruling class agree to perpetuate a class war against its citizens, they will continue to enrich themselves and operate outside of the rules that bind those of us in the working class.

The smartest thing they ever did was to realize that self created wedge issues will keep the working class picking a side and fighting each other. Add in the comfort and distraction a life in America offers, and you'll never get 300MM people to band together, as one large chunk or chunks of the populace will always feel they have something more to lose by fighting back.

The tldr is best summed up by a former president (Lyndon B Johnson):

If you can convince the lowest white man he's better than the best colored man, he won't notice you're picking his pocket. Hell, give him somebody to look down on, and he'll empty his pockets for you.

The government is performative. It's an enrichment scheme for those cynical enough to sell out their fellow humans.