Mass extinctions are common in nature
Earth has experienced 5 mass extinctions. More than 99% of species that existed are now extinct. Time and time again, the reign of a species have fallen with an abrupt ending.
For example, ocean/atmosphere chemistry, climate change, volcanic activity and meteor/asteroid impacts had fatal consequences.
No matter how far back you look, nature has found its way to reshuffle the deck. Large mammals are at greater risk.
For example, giant sloths, mastodons and saber-toothed tigers became extinct only about 10,000 years ago. They just couldn’t find a way to outmuscle nature.