Life isn’t zero sum.

That is the crux of it. They believe it is. Wholeheartedly. It's part of their core being at this point. If someone is receiving something, they must be losing something in return. It's their tax money.

They're incapable of making the mental connection that corporations and the rich aren't paying anywhere near even a fair share of taxes that could entirely pay for those programs to apply to every citizen, including themselves. And the media preys on that to further pit themselves against their fellow citizens because it's all owned by those same rich assholes.

It's not even just that, they believe that people on government assistance need to be constantly shamed and humiliated, otherwise they will never have the motivation to pull themselves out of poverty.

I had an argument with a big-L "Libertarian" acquaintance who straight up admitted that he would rather pay more in taxes to implement new stricter oversight and systems to restrict what people spend their WIC/SNAP benefits on than endure the possibility that someone might buy a bag of Doritos with said assistance. The cherry on top was him--again, a "Libertarian"--claiming it would be to ensure they are making healthy, state-approved, food choices.