Despite the Declaration of Independence, it's not the State's job to promote the general welfare of its people. It IS the state's job to protect private property.
Why one and not the other? Let me look for some youtubes that will explain it.
It's largely been created and fostered by right-wing rich guys to peal back the New Deal. It's an intellectual complement to hard-core anticommunism, Islamaphobia and religious fundamentalism. A very Leninist strategy.
It borrows heavily from anarchism but tosses the whole collectivist thing and fabulously imagines that markets can exist without states.