A negative, selfish mentality characterized by a preference for others not to get ahead of or do better than oneself. It alludes to a phenomenon of a group of crabs in a pot, in which an escaping crab is pulled back down by the others so that none escape in the end. She dreamt of going to college and beginning a better life, but her parents' and friends' crab mentality constantly discouraged her from leaving the sordid life in which they were entrenched.
the belief that you must protect yourself because other people are going to attack you Many designers develop a siege mentality because they're terrified someone will steal their ideas.