Why do people who seem to have it all commit suicide?

2 of my fav YouTubers from back in the day committed suicide, both seemed very happy about their lives, they seemed to be doing well financially and at least seemed to have a lot of friends and family who supported them.

I know what we see and what is going on in their lives are completely different perspectives, still, when their friends and family went public about it, they did mention they never saw it coming and, y'know, all the "he was such a happy person, I would've never expected that from them" comments.