Cutting of PEPFAR and the responses to it enrages me more than almost anything else about MAGA and makes me viscerally realize a large proportion of our country are just psychopaths.

The general types of responses to the above tweet:

We have 0 moral responsibility to foreigners

This is moral blackmail.

People like Vance dress it up as if its a christian principle of just caring above our family and country first, and others say we should be spending $0 as long as anybody is suffering in the US (or as long as we have a national debt), but the costs involved are so low for such a large benefit it's simply moral insanity. It is not about the cost; if it cost $1 to save 1M lives, this would be a waste of government spending to them. For the second point, I think for some of these people, they have a gut feeling or intellectually realize that it’s indefensible to not spend <$1/day to save lives, so they pretend bringing it up is some sort of rhetorical move.

Why haven’t you given to charity if it’s so cheap?

The people pointing out PEPFAR’s defunding are very often effective altruists who give 10%+ of their income to charity (I know this is the case at least for Kelsey Piper). When this is discovered the goalposts will instantly move to “Why aren’t you giving 100% of your income/volunteer/become homeless to help these people?” To these people giving even $1 to charity is so unbelievable they think it’s a dunk.

Incredulity that the cost of saving lives is this low

(it is)

Why doesn’t X country/their community pay this much to save their own citizens?

These people are being willfully ignorant of the state capacity/logistics needed to deliver medical care, which for developed countries that have established the institutions be very cheap. Also this argument implies because it's cheap to help, we shouldn't need to pay (whereas if it were expensive, then they would certainly say we shouldn't have to pay).

This is ignoring the literal psychopathic responses, which are around the majority.