It's the institution.
Public unity has always been the establishment's greatest fear. The powerful have always created institutional circumstances that would exploit some people more, some people less, and other people in different ways, making it acceptable for each group to point to the others and say, "They are the cause of all our problems", creating public division and perfectly camouflaging the real cause of all their problems (institutional circumstances, created by a greed-controlled establishment that promotes and allows for selective exploitation, INTENTIONALLY keeping everybody divided, with the ultimate purpose of preventing public unity, the establishment's greatest fear).
The institution sets the table. People simply behave according to the circumstances in which they're thrown.
Those who are exploited less (the privileged) will accept quite a few advantages of that privilege, and justify it as a means of survival and upward mobility.
Those who are exploited more will accept quite a few justifications for retaliation against that privilege, and advocate those as a means of survival and upward mobility.
The institutional establishment (those in power) set the table, which allows for selective exploitation, to protect themselves from public unity (their greatest fear).
The people don't have a chance unless we can unite against the establishment that creates the institutional circumstances.
As long as the little people blame each other, the institution will always win.