At a very high level, the problem is almost intrinsic; it is very difficult to stop a determined attacker given the current balance between defensive and offensive capabilities. A strong focus on hardening only makes it expensive, not impossible.

That said, most security breaches like the above are the result of incompetence, negligence, ignorance, or misplaced trust. In other words, human factors. Humans will continue to be a weak link across all of the components involved in security. There comes a point where systems are sufficiently hardened at a technical level that it is almost always easiest to attack the people that have access to them rather than the systems themselves.