

Introverts exist, and are… very often fine with solitude, prefer it generally over socializing.
But they are generally fine at participating in society and living normal lives.
Healthy people… do need doctors … and therapists.
A person can outwardly appear to be healthy… and actually not be.
Preventative medicine, regular checkups, your body changes as you grow, and habits you develop in your youth may need significant reworking.
Therapy can give otherwise healthy people a method of exploring their inner selves more fully or more consistently… they can teach them frameworks for understanding and dealing with other kinds of people, for being better able to deal with kinds of trauma they have not yet experienced.
Also… same with physical health… people with some nascent mental problems or patterns forming… probably won’t be obvious to a non specialist, untill it gets more severe.
My entire point is that you are just overgeneralizing, in general, and saying rather silly things.