I don't "assume", I induce. See Newton's rules of reasoning. Pay particular attention to Rule IV.
It is clear from many examples that rationality gives us the utmost ability to adapt, prosper, and survive over the long term. And there is no example that truly leads in the other direction. (There are many perverse definitions and applications of "rationality" that seem to trick some people into thinking it does lead in the contrary direction).
Your deranged sarcasm eloquently sums up what's wrong with our educational system: kids are taught that their opinions matter, regardless of how idiotic they are. Well the truth is, your uninformed opinion doesn't matter.
