If a tiger attacks you, it will go for the neck and you will die. Chimps attack humans just like they attack other chimps, and that means going for the face, hands, and genitals. I'm not even sure there are any humans who've been killed by them. They just horribly torture people and let them live.
It's hard to ascribe evil to an animal, but chimps are clearly working on it, heading up the evolutionary ladder.
We're genetically related, so it shouldn't come as a surprise that our closest cousins are also mean as hell. We didn't become the apex predator of this planet for no reason.
Because they are smart. With some luck you can trick a tiger. Much harder with a chimp.