Unfortunately it happens. We all ask why when it happens. A former business partner and a BIL both committed suicide for unknown reasons. I won't go into details other than to state one shot himself in the head and the other hanged himself. It was totally devastating to their family members.
I know someone who hanged himself outside his mother's home, which was an act that I am sure absolutely destroyed her when she found his body the next morning...yet he absolutely loved his mother. He had the most beautiful daughter, who he also absolutely loved, and he was one of those really happy people. However he was hit with some deep depression that he hid from those who knew him, and I think it got so bad that he went into that dark spiral (where your mind starts feeding on itself, and you end up believing you are useless/worthless etc). He went to the place he knew as home, and killed himself. Before that I used to think suicide is for weak cowards, but after that (even though I still strongly believe it is the cowardly way out) I came to recognize deep depression as something that needs to be immediately taken care of. Immediately. Whether it is you getting depressed, or a loved one. Because the moment that 'dark spiral' (my name for it based on the people I've seen) hits, the chances of getting out of it are the same as getting out of a plane in a flat spin. Possible, but difficult.
In my occupation I have seen people worth hundreds of millions of Euros kill themselves (and in some particularly gruesome ways) when they lose a couple hundred million. Yes, losing 200 million Euro is a mess, but you are still worth over 400 million, and you have a fabulous family. Why kill yourself? The dark spiral. The moment you start reinforcing your negative thoughts, and start seeing yourself as a burden to your family, the fact that you have a loving caring family actually works against you. Deep depression is something that, once identified, needs to be immediately taken care of because, and I kid you not, someone in a deep depression is not normal at the time. Logic is not working, and the person is more or less in an insane state of mind. Such a person will kill him or her self, even when logic dictates otherwise. At that moment that person is having abnormal thought patterns/processes, and it doesn't matter whether they have a loving family, a great occupation, a healthy bank account, a couple of hours to Thanksgiving ...the person left rationality and logic and is heading straight to destroying himself unless something can be immediately done.
That is how Navy SEALS shoot themselves, or rich financial titans slit their wrists or throw themselves in front of trains, and loving sons and dotting fathers hang themselves in the backyard.