The typical citizen drops down to a lower level of mental performance as soon as he enters the political field. He argues and analyzes in a way which he would readily recognize as infantile within the sphere of his real interests. He becomes primitive again.
-Joseph A. Schumpeter, Capitalism, Socialism, and Democracy
In other words, politics is the mind killer.
I think it may be wiser to say “policy is the mind killer”; it emphasizes the cross-institutional cross-scale pervasive nature of political thinking.