Well, he picked a good place for a nice safe home invasion. Boston residents aren't allowed to keep firearms in their homes.
To survive in a state like that you have to think like a criminal and know what the criminals know about how to hobble the police. It requires a real mind change.
A lot of criminals gain much street knowldge because the ACLU has given the many rights. Their lawyers teach them about what to do in the situations they get into. Honest citizens only know a fraction of the tricks they use to evade prosecution. I wish there was a book.