The basic dynamic is: if you advertise a rule, and then don't enforce it, you in-effect reward people who transgress the rule and directly discourage people who obey it - and then wonder why you are "surrounded by assholes," when what you've done is set up a filter that only assholes manage to permeate. I think of this as a variant of, the "Hock Principle: Simple, clear purpose and principles give rise to complex and intelligent behavior. Complex rules and regulations give rise to simple and stupid behavior."
More than post-hoc explanation, it can predict a pattern for how large organizations and bureaucracies have clusters of terrible people at the top, how an individual may develop a pattern of being subject to abusive relationships, how some social programs will just sustain the problem they are mandated to mitigate, how corruption spreads in institutions, how some people always seem to end up in terrible jobs, and even how discussion forums can turn toxic.
It comes down to the maxim, "what you reward, you get." If you do not set boundaries and then enforce the boundaries you set, the only people who will pass through them will necessarily be the kind of people who don't respect you or your boundaries. Set boundaries for yourself and how you relate to the world and others, and be absolutely aware that when you choose to relate without them, you are rewarding people for not respecting you. Do the same in your companies, products, services, and teams. If you have ever worked with someone who was an asshole and wondered why and how they were able to succeed, it is because the people around the person let it work for them.