What makes a person become insane?

marriage and children

What is your definition of "insane"? Do you mean someone who is psychotic, simply neurotic, or has a personality disorder? "Insane" is a lay term, and has no meaning in medical terms.

Well, you can either refer to numerous mental illnesses and ask about insanity in criminal law - but as said already, a specification/description would be nice.

If you define "insane" as "unable to cope with daily life" the answer is probably some combination of genetic weakness combined with a stressful life.

Am I losing My mind?
I've been "bothered" most my life, seeing more I think than most people see when they look at the world. Why do I feel like I'm trapped on a planet full of brainless monsters hell-bent on destroying it for their god? Why can't we have laws that effectively strips any DIRTY politicians of EVERYTHING they've "earned" and any benefits they would have received? Why do I see nothing but brain-washed children coming out of churches? Why Can't We oust a Politician Ourselves if they did nothing but lie to us to get Our vote? Why can a christian kill their children and still be a "good" person but myself (as a non-believer in anything that says everyone HAS to die for their religion to come to it's violent bloody climax) am looked upon as a monster? Why can We afford to attack countries that have done nothing to us but We can't afford to save Our Planet? Why am I so disgusted to be a human?
I told you I am bothered.

Natural Variation.

Troubled is the natural condition. Because all the various possibilities in the universe are simply thrown together to fight it out, every single person is in conflict with something. Self-centered people mingle with altruistic people. Moral, immoral, constructive, destructive, large, small, bright, dim, ... every kind of person you can possibly imagine grows up together and just churns around with no rhyme or reason.

Because it's a wild free-for-all, anyone who has a wish or a goal about how things "should be" is faced with a lifetime of struggle to make it so. Trouble, I tell you. All the best stuff in life is nothing but trouble.