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crab mentality

n. (context idiomatic English) 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 in which one tries to escape over the side, but is relentlessly pulled down by the others in the pot.

Wikipedia
Crab mentality

Crab mentality, sometimes referred to as crabs in the bucket (also barrel, basket or pot), is a way of thinking best described by the phrase, "if I can't have it, neither can you." The metaphor refers to a bucket of crabs. Individually, the crabs could easily escape from the bucket, 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 claimed to be that members of a group will attempt to negate or diminish the importance of any member who achieves success beyond the others, out of envy, spite, conspiracy, or competitive feelings, to halt their progress.