The Dodo was a large flightless relative of the pigeon, known only on Mauritius in the Indian Ocean. Exposure to European sailors did them in, and in thirty years, Dodos were all gone. They were not stupid, they were trusting and curious.
Nature is always shifting things around, and in the shuffle, many species disappear. It is a Natural process, We think. Then everything gets recalibrated.
The Rhino Day will doubtless come. Or perhaps it’s here. The possibility exists for every species.