He rose to one step beyond his level of incompetency...and then attempted to make a superhuman leap beyond even that.
The Peter Principle, while more of a cutsey idea than a legit provable idea, is definitely real.
"In a hierarchically structured administration, people tend to be promoted up to their "level of incompetence". The principle is based on the observation that in such an organization new employees typically start in the lower ranks, but when they prove to be competent in the task to which they are assigned, they get promoted to a higher rank. This process of climbing up the hierarchical ladder can go on indefinitely, until the employee reaches a position where he or she is no longer competent. At that moment the process typically stops, since the established rules of bureacracies make that it is very difficult to "demote" someone to a lower rank, even if that person would be much better fitted and more happy in that lower position. The net result is that most of the higher levels of a bureaucracy will be filled by incompetent people, who got there because they were quite good at doing a different (and usually, but not always, easier) task than the one they are expected to do."
Clark is no dummy, but to be fair, he isn't nearly as skilled and savvy as he thought he was. A classic case of the Peter Principle at work - he rose to a level he wasn't well suited to, and rather than accept that, he beleived his publicity and went for a notch even higher. All the seams started showing.
The rest is history.