Bush came out of the oil production industry. Not refining or distribution, both of which require a great deal of industry expertise for anyone to succeed, but production. He used other people's money and gambled that the next oil well he drilled would be successful.
Oil Production is a "Bet your company" industry. You don't need a lot of expertise - you can hire that. What you need is the willingness to bet large sums of (other people's) money to a drilling operation. Win and you are rich. Lose and you are bankrupt - and then you go on to set up a new company and try again. That is the core culture of the industry.
Bush operates by making decisions based on his intuition. He also does not go back and reevaluate his failures. He doesn't even want to hear about his failures, or he wants to blame someone else.
These are techniques which lead to the best chance of success for individuals in the oil production industry. They also consider the organization needed to accomplish the job of drilling the wells as disposable and unimportant.
A person with that professional background needs to be highly intelligent and very intellecuutally curious to make an effective transition into government. Even then it will be extremely difficult.
In government, the organization operates on routine which is based on very wide social acceptance, and is far from disposable. It is one of the sources of stability for the society that it is central to. Replacing a government organization ususally involves revolution and extreme social disruption.
With his lack of intellectual curiosity and his dependence on making decisions based on intuition (meaning based on his socialization and experience), George W. Bush is a guaranteed failure when being placed in a government top management job. He doesn't have a clue, he doesn't want to hear that he is failing, and he doesn't have the curiosity to determine what is actually going wrong with his decisions. Instead he will want to know who is to blame, because it can't be him.
It really is that simple. Bush is the worst single President America has ever had, and it was totally predictable.