It turns out that cheetahs, having sacrificed strength and size for speed, are over-specialized. They eat pretty much just gazelles and small antelope. So what happens when they can't find gazelles? They go hungry.
Even their jaws are just large enough to hold a gazelle's neck, but not large enough for other animals.
That's how they catch gazelles. They chase them and when they get close they reach out a paw to trip it. It may take a few tries as the gazelle goes down and gets back up again. Finally the cheetah is able to get its mouth around the gazelle's neck, a perfect fit, and it holds on until the gazelle goes limp.
They're not strong enough to fight off scavengers. When hyenas show up to steal their kill, the cheetah just abandons it, no contest.
I was watching on TV a cheetah standing in the middle of a giant herd of something -- not gazelles, something a little larger. They weren't afraid of the cheetah at all. They knew. The cheetah was looking around at all these animals, in the middle of literally tons and tons of meat, but there was nothing he could do. A lion would have had a field day, but the cheetah just looks around, hungry.
Here's the Cheetah Conservation Fund. The main threat to cheetahs is of course loss of their natural habitat.