Why do so many people choose to commit suicide?

at the end of the day people who say coward really have no idea of what was going on in the persons mind, I think its a really unfair thing to call someone. In my experience people mostly commit suicide because the loss of a loved one (either relationship separation or death), humiliation (being bullied for years) or are in dire financial difficulty. It's a real shame however, as time usually solves most things, but they just cant wait any longer