To address all of your points seperately-
Many fighters have completed masters degrees or phds, or at least 4 year college. Just because someone enjoys gladitorial hand to hand combat does not correlate with lower IQ.
MMA has never had an injury like the recent one that unfortunately happened in the NFL.
There are more deaths per year in boxing and high school football than MMA, which has 0 deaths in sanctioned fights. Boxing deaths occur mostly in "toughman" or instances when weight cutting and head trauma are both very excessive.
Many fights end without a fighter taking heavy damage due to tapping out by submission.
Trained medical professionals are always on hand and ready to stop the fight after ONE knockout instead of many as in boxing or kickboxing.
And finally, MMA represents a revolution in the way martial arts are practiced and understood, and the heroicism, athleticism, and skill and sportsmanship of the competitors definitely showcases MMA as one of the most, if not the most, challenging sport in the world, physically and mentally.