It's hard to know, and many people need these medications or they cannot function at all. Maybe some of it can be bad decisions made in life, some of it is bad decisions and behavior towards them, and a lot of it is genetic. I don't judge people, and have known many different types. In my experience, people who drink too much are more abusive and engage in erratic behavior worse than most of the mentally ill I have known in my life, especially once they have been stabilized with meds.
There are many people out there who have made far worse decisions about their lives, like really badly hurting people and especially children, and they are not diagnosed as being mentally ill, they function well in their daily lives except they commit horrible crimes; they don't have mood swings, etc.; there is no drug that will help them be any different. They live to ripe old ages and die of natural causes, leaving a trail of grief behind them.
I would hope someone close to you doesn't come down with it and have to endure the stigma, cruelty, joking and disparaging remarks by some people about it. Fortunately, many people are really kind and understanding. So many families, nice parents, have someone with it now.
I remember when Prozac was initially released. It was almost a miracle drug to those with depression. They didn't have to wait forever to see results or suffer the side effects of the other anti-depressants. However, some doctors saw Prozac as the pill for depression, give the patient Prozac and never see them again. We saw a lot of PRN prescriptions come through initially (fill for a year upon patient request.) Wrong move, but Eli Lilley & Co sure didn't let a lot of info out on Prozac.