Why is that so often things so obvious to me like drug prohibition increases violence and health issues rather than drugs themselves, but for so many people it

Why is that so often things so obvious to me like drug prohibition increases violence and health issues rather than drugs themselves, but for so many people it is difficult to comprehend - like they can only make a simple connections aka drugs are bad, therefore violence and health issues. Like if they were not capable of incorporating more than two variables in their thinking. Then such people also seem to be dominating in the political scene. Do such limitations in thinking give some kind of advantage when it comes to entering politics?