Gang bangers are insecure about themselves. Insecurity at its worst.
Gang bangers have no moral compass. They’re insecure because they know this and they seek refuge in the power of the pack.
But of course that seems to be true in American society as a whole now. People don’t accept individual moral responsibility and they turn all their actions over to a group (an ethnic group, a political group, etc.) that is not acting on the basis of ethics but on the basis of the power to intimidate.
All those people participated and all those people watched because they were dehumanized and incapable of independent moral action. That may sound old-fashioned, but that is what it is, even now in the 21st century.