https://en.wikipedia.org/wiki/Crab_mentality

The metaphor is derived from anecdotal claims about the behavior of crabs when they are trapped in a bucket. While any one crab could easily escape, the claim is its efforts will be undermined by others, ensuring the group's collective demise.

The analogous theory in human behavior is that members of a group will attempt to reduce the self-confidence of any member who achieves success beyond the others, out of envy, jealousy, resentment, spite, conspiracy, or competitive feelings, to halt their progress.