crabs-in-a-barrel 

A syndrome where a group of like situated people hurt those in their community attempting to get ahead.

Often this is applied to people in an impoverished community where one person is starting to get ahead. The collective community becomes jealous or filled with a sense of self-loathing, so they find a way to pull that person back down to the community's level.

When harvesting crab, the crab as a group will pull down any crab that starts to climb out of the barrel in an attempt to be the first out of the barrel that holds them in, hence crabs-in-a-barrel.

crabs-in-a-barrel by Sole Admiral December 30, 2009