Crab Theory (or Crab Mentality) is the observed behaviour of a group of crabs in a bucket with no lid. Although any crab would be able climb out and escape if they tried, when doing so the rest of the crabs will hold the crab back. I didn't know that crabs did this.
Parallels can be drawn to human behaviour of "if I can't have it, neither can you".
Born dyed in the wool
Never knowing of a belly half full
So many of us just crabs in a barrel
With no feasible means to escape the inevitable cull
