If i were the devil, by day I'd be preaching about how great it is to live in sanctuary city, by night you would recoil in horror of the menace I'd be. I'd start by engaging in the usual tricks used by landlords to scare off rent controlled rentors to replace them with illegal immigrants. I'd lure gangs to conduct activity on the grounds, every resident would be paying me on the side one way or another, be it cash, women could be pimped out, the kids can sell drugs, or they'd find themselves on the wrong side of the gangs. I'd never have problems finding a fix for politicians and police chiefs looking for bribes or needing to be blackmailed. This is a tremendously bad idea.