Well you can't just claim that based on nothing. I agree it would take a lot of people to calculate. But until we do, we can't assume stuff, surely you know that's not how the scientific method works.
And leopards hunting giraffes for food is a prey/predator relationship, even if they only do it when there is no weaker prey available. Just because giraffes are harder prey, doesn't not make them prey.
Whereas there is no such relationship between eagles and humans. An eagle won't actively prey on a human for food. They will attack humans, if they feel threatened, but that's not prey/predator relationship.