I would cite heroin users, thinspo anorexics, (real) Neo-Nazis, some varieties of paedophile, and credit card skimmers as examples of communities with their own

I would cite heroin users, thinspo anorexics, (real) Neo-Nazis, some varieties of paedophile, and credit card skimmers as examples of communities with their own unique cultures (disclaimer: often awful ones) that are counter to the mainstream. The first two you can maybe make an argument for being integrated into the mainstream, but the last three are totally against the current culture.