Why do cute little kitty-cats purr, and rub their cute little heads on your ankles?
Simple ...
They're sucking up. Kissing ass. You outweigh them by an order of magnitude, could smash them to a pulp if you wanted to, and they know it.
If they were big enough to rip your throat out and eat you, they'd happily do it.
Sort of like mountain lions ...
Yep!