Often the individual animals preying on humans have some sort of health problem or something along the lines, making them desperate and thus continuously dangerous - so it is easy to pretend we don’t do it for vengeance too. There’s also the weird still lingering belief that once an animal has tasted human blood they’ll want more. Humans like to believe we’re not controlled by instinct and make up explanations for why not, but our actions have more truth than our words