As human populations became larger there became a desire or need for a structure to help provide some insulation, some control, some protection from the lessors of our species. A system to create and enforce rules in an attempt to curb violence and theft. A system to protect groups from neighboring group attacks. A system to stabilize economies. A system expected to prevent the unknown from happening.
Among the thoughtful there is no need for systems, rules, or governments. The thoughtful examine the effects of their actions and behave accordingly. The thoughtful do not need laws to tell them that murder is wrong, that stealing is wrong, that attacking your neighbors is wrong. There is no need for the threat of an army, no need for economic interventions, for the thoughtful think about their actions and act accordingly.
All these things, these laws, these systems, these governments, were created because of those unwilling to think. Those driven by selfish desires. These structures were built to offer some protection or recourse for the actions of the self-centered. In this process however, decisions made to protect form the thoughtless allowed a society to increasingly believe that they themselves did not have to think as much because of their political creation.
Systems and laws were put in place and citizens of these governments increasingly began to have faith that these dogmatic ethos would take care of all situations resulting in more and more people moving away from a thoughtful way of life and relaxing into a more self-focused existence. This is true of all types of governments.
A self-focused existence quickly leads to thoughts and desires of power and riches. There may be no easier place to secure such things than though politics. Before long the governments have high concentrations of no-longer-thoughtful citizens filling their offices. Those who are not thoughtful are responsible for protecting the populous from those who are not thoughtful. It does not take much to realize why those who are thoughtful would not find politics a particularly appealing situation to enter into.
Inspired by Walter i might say that this explains the "why" but does not help justify "what for". Knowing what disease you are inflicted with only offers so much relief before you start to long for a solution, a treatment. In this self-focused society i find myself a thoughtful man trapped in that void between the diagnosis and the cure.