For some, depression is an episode or collection of episodes in life. For others, it's a chronic condition. He lived decades (from other accounts) with a chronic condition and succumbed to it.

Sometimes, toxic environments contribute and I don't want to suggest otherwise, but for those with chronic unipolar depression, it is a condition that people die of. It's sad, but so long as we understand that it's illness, we can get over the polemics.