Quicker8...

" Crab mentality, sometimes referred to as crabs in the bucket, describes a way of thinking best described by the phrase "if I can't have it, neither can you." The metaphor refers to a pot of crabs. Singly, the crabs could easily escape from the pot, but instead, they grab at each other in a useless "king of the hill" competition which prevents any from escaping and ensures their collective demise. The analogy in human behavior is that of a group that will attempt to "pull down" (negate or diminish the importance of) any member who achieves success beyond the others, out of jealousy or competitive feelings.
This term is broadly associated with short-sighted, non-constructive thinking rather than a unified, long-term, constructive mentality. It is also often used colloquially in reference to individuals or communities attempting to "escape" a so-called "underprivileged life", but kept from doing so by others attempting to ride upon their coat-tails or those who simply resent their success.[1]
It describes a desperate lust to pull other people down, denigrating them rather than letting them get ahead or pursue their dreams. It is an unwillingness to allow someone to get out of dire or bad life situations, often being foiled by friends and family members who keep sucking them back in. This trait can strike at several levels of life, like in office environments, particularly on promotion. It is a reflection of the famous saying “we all like to see our friends get ahead, but not too far ahead.”[2]