To be predatory you have to go out of your way to take things from someone else.
It'll quite often be the life of another creature.
Here's a rather common predator you might spot today:
It's not just the eating of other creatures that makes a predator (a trip to the butcher doesn't count) but the taking-without-leave. The theft has to have a substantial effect on the victim, too: a cleaner who keeps stealing toilet rolls from his or her (yes, yes, other genders are available) employer isn't predatory unless the place makes toilet rolls and this causes the factory significant and continuing loss.
Being on the look-out for predators is probably hard-wired into the brains or more or less everything on the planet that has a brain.
See how much time you spend trying to Spot the Predator today.
You'll probably get suspicious every time something arrives in your junk mail folder, for a start.
Spot the Frippet: a predator. This word comes from the Latin praedārī, to pillage, from praeda, booty.