I suspect that most people are "cured" or at least don't deal with this as a lifetime illness. Because they had one episode, probably not so serious, they may or may not have sought medical help and probably never looked for a website like this one. It is those of us who deal with it on a longer term basis that search for answers and so we may make it look like most people deal with this on a lifetime basis.
I know few people that live with depression as a life illness. I know a few people that take an antidepressant but it doesn't seem to mean much to them. They don't go to Pdocs or therapy. They don't talk about recovery or hospital stays. If they knew what depression meant to me, they would be totally shocked. I can't imagine a day without this veil; it's just how heavy the veil is going to be that varies. So yes, I think most people are "cured." Someday, I hope medical science can do the same for everyone.