You're right people will never ride a horse instead of their car. (Plus it seems horses would be worse for the environment) But the 2k people who own 50% (?) of world wealth have more say on how the resources are used than the 99.99% of other people. And like them those 2k don't want to ride horses. On the contrary they want to use all the resources for their own benefit. So getting ride of them could allow to implement some sustainable practice they are fighting against.

But it is a joke in the end: Having 2k oligarchs run over by a trolley wont save the planet. What need to be run over is the system that allow 2k people control the fate of all the others through greed.