It’s a fundamental lack of understanding of math and science.
There’s a video going around conservative circles talking about how CO2 only makes up .04 percent of the atmosphere, and therefore even if it were doubled it would be less than 1/1000th of the atmosphere, so it’s not worth worrying about.
I tried to explain to my father that that’s exactly why we’re able to have such an impact. They don’t understand that we’re able to make a much larger relative impact on CO2 versus Nitrogen and Oxygen and therefore a larger impact on global temperatures.