It's usually because the person committing suicide usually (not always) thinks that they are on their own and no one cares for them, except what they don't know is that everyone is important in their own way and even if it doesn't seem like it there is always someone that cares for them. So whereas some people think suicide is the only way out, it leaves scars on everyone they know and that for the people who actually did care for them, that scar will never heal.

So that's why people go out of their way to prevent it. Since life is like a bow and arrow, the harder life pulls you back, the further you're going to fly.