Poverty breeds violence and crime.
Read about the 19th-century 'scuttling' gangs in the shitty parts of Manchester.
Of course, it doesn't help that the criminal justice system is on life support. Due to - guess what? - Tory cuts. See also the Youth Service, Surestart, you name it.
Treat people like shite - 'welfare' cuts, poor NHS, poor schools, poor practically everything - and they will react in ways you don't like. What's more, the Church, which used to help with social control big time, is virtually out of business.
Oh, and lionising greed and acquisitiveness hasn't helped either. You see you're 'nothing' unless you have a big car, a big house, massive salary. All the stuff these kids can't hope to get legally.