That's easy: because the side advocating about climate change wants to come into your home and ban your gas stove, your gas water heater, your gas yard equipment, and your vehicles and replace them with "less efficient" versions. There is a ton of "pay more for less" FUD, and just enough of that FUD is or was true for that crowd to see it as a money/power grab.

The side against it is then amplifying all of that while blaming higher prices on the killing of coal and gas while spouting laissez faire freedom propaganda.

The global warming doesn't exist side believes it is a grift the same way everyone outside the MAGA bubble believes the Alt Right influencer/commentator shit is a grift, or the Flat Earth movement is a grift. There are enough grifters and true believers in any system that can be cherry picked to reinforce any individual's viewpoint.