They aren’t hard to see in a lot of areas if you drive down a dry riverbed with a light at night! Plenty of leopards! My last time there, the guy I was hunting with was recovering from a leopard bite in his left arm.
The problem is not that leopards (or other big cats) are already extinct, but rather that their numbers have dwindled at an unsustainable rate.
Compare the population of big cats just 100 years ago to current time. These cats have been around for many millenniums at stable population numbers. Current numbers are smaller by orders of magnitude. Without these carnivores expect overpopulation of herbivores who can denude forests in excess numbers.
So it is not a stretch to posit that the carnivores are contributing to climate stability.