Necessary suffering for writers?

One quick look at the history of accomplished writers will show you that a good number of them committed suicide. To someone like myself, that fact alone causes feelings of unease. If someone, such as Sylvia Plath for example, reaches the pinnacle for which all writers strive to achieve and has that coveted position hold no joy to them, it brings to mind the inquiry if such a place of achievement holds any joy at all, what-so-ever. I've often noticed that, while still living, the lives of many accomplished writers was anything but enjoyed by them. Many were plagued by depression and incurable sadness, regardless of any quirks their success brought to them. One has to simply wonder since, so many were affected in that way, is such a condition necessary to thrive in literature, regardless of genre. Its a question I cannot, myself, easily answer. If one doesn't possess within themselves a sort of inner conflict that continuously forces them to create and express, would they still still carry on as writers? Many great writers of the past were also afflicted by addiction, no doubt fueled by these same inner 'demons'. I suppose I will never know the answers to such questions. But, as trivial as it may sound, I find myself a degree thankful for their suffering. For if such instances did not occur, perhaps none of us would ever be graced by their creations and life itself would be far lesser without them.