Slothfulness Is A Defense
It turns out that nature has equipped the sloths with a brilliantly simple way of avoiding predation — moving very, very slowly. While it’s probably a myth that standing still would stop a T. rex from seeing you, it is nevertheless much easier for predators to spot a moving target. By moving so sedately, the sloth blends into the canopy from which it hangs.
No need to run away from a predator if the predator never notices you, but sloths go further than that.