I find your argument somewhat specious. Terraforming entire planets in a few hundred years is feasible, if you devote significant resources of the entire human

I find your argument somewhat specious. Terraforming entire planets in a few hundred years is feasible, if you devote significant resources of the entire human race to it i.e we have had a drastic impact on the climate by pumping trillions of tons of carbon into the atmosphere. The equivalent effort on Mars would be impossible due to cost, but on earth it was a by-product of an already profitable process (extract and burn fossil fuels, cut down forests).