1) Nine out of ten adults live a mentally health life. The one who doesn't experienced/has experienced traumas.
2) Every men lives a mentally health life. If he doesn't, he experienced/have experienced traumas.
Both of these are really clunky. I would write them as
1) Nine out of ten adults live a mentally healthy life. Those who are left have experienced trauma.
2) Most men live a mentally healthy life. If he doesn't, he experienced trauma.
Ideally that idea would better be portrayed by an entirely different sentence. Something with more gravitas.
Most people live a normal life. Others experience traumas the rest can not imagine.
If it's for a more academic work:
While 9 out of 10 adults live normal lives, a good number still experience trauma.
These sentences are, of course, factually incorrect as nearly half of people experience some kind of mental distress. Hope this helped