There is this sick cult-like mindset in many organizations, most notably in sport teams, and among a few civil servant jobs (police officers, firefighters, corrections officer). Its either, "Youre with us, or you're against us" mentality. I knew this guy who became a firefighter, and dropped all of his old friends. His new friends were all firefighters. Whenever parties or bbqs happened with families, all the firefighter buddies were invited, no other friends.
Its like you join these organizations and you're brainwashed. Interesting study in large group dynamics.