I think you are getting your ideas of what a majority and a minority are. Gang culture accounts for a small minority of the UK's black population and those that do escape from that life are not hated and vilified by anyone other than the small minority that remain within that lifestyle.
Gangs have been prevalent within inner cities for over a hundred years, across all ethnic groups and at the moment we are focusing on youth gang culture that has largely been imported from the United States.
You also don't seem to grasp the basic point that Black Culture is not the same as Gang Culture.
This has got nothing to do with oppression of their ancestors or any innate culture clash, it has to do with criminality, social deprivation and their lives now. Those bringing up the Atlantic Triangle are as guilty of ignoring the real issues in our inner cities as those who are focusing on the skin colour as the reason for their criminality and antisocial attitudes.
Focusing predominantly on the colour of the criminals is counter productive and will only alienate those within those communities who are law-abiding and potential role models for those who would grow up alienated and more likely to follow in the footsteps of the criminal element of these communities. We need to engage these people while at the same time punishing those who break the law and blaming their skin colour does nothing but make the situation worse than it already is as it gives the criminals a justification for their actions that simply doesn't or shouldn't exist.