The Willie Sutton Theory of Cyber Security
Okay, students of history know that Slick Willie Sutton denied ever saying the famous quote attributed to him, but regardless of who said it, criminals do rob banks because that's where the money is. Or at least that was true back when our cash was physical instead of a bunch of electronic signals. The point is that banks understand how to protect the cash they do have, by placing the strongest controls immediately surrounding it (the vault) rather than focusing on keeping people out of the front door.
Network security specialists, on the other hand, are still putting way too much effort into protecting the perimeter, according to this article form Alan Cohen published over on SecurityWeek.