It's convergence of belief, evidence and outcome. You can have all three, or only one. It's not necessarily by intent or design, although it certainly seems to be both.

Denying the outcome benefits Russia more than anyone else appears contrary to evidence. I have yet to see a reasoned justification of how this benefits the USA beyond the awfully short term trite "saves money"

About why, or how Trump has come to enact these outcomes I cannot speak, but they don't seem to be benign for longterm US political/strategic goals. It's like a retreat to an older isolationist world view combined with a "fuck the liberals" mentality.

I used to believe in the power of the military industrial complex and its beltway lobby. I begin to doubt it, because almost all of the US aide to Ukraine was spent inside the US materiel production industry. Which is also the truly bizarre thing: he's cutting almost Keynsian pump priming domestic spend. It's massively bad for jobs.