I think the lot you mention have a superhuman ability to bounce back from just about anything, however this is contingent on not having experienced severe and sustained trauma. Everyone I know who suffered chronic abuse during childhood now lacks the capacity to wield the optimistic brush that will paint life with color.
I have known some people whose biggest worry in their life is work stress, being unable to buy fancy cars, losing their phone charger, or feeling bad because they waited till the last minute to turn in a uni assignment. These people can see the positive in everything, because they have been blessed to never have truly peered into the depths of hell.
There are things we all must cope with, burdens every human must bear, like eventual loss of loved ones, failure, accidents, etc, but I sincerely believe that once you have sustained enough damage in this life, like the aforementioned events or traumas repeated over and over again like a demented broken record, it's impossible to ever have the mindet of a blind optimist again.
Anyone I know who seems content with life and exudes unbridled positivity is always immersed in a distraction. Whether it be work, school, drinking at pubs, having a very robust social life, having family they can spend lots of time with, traveling, binging TV shows, they are never alone with their thoughts. I think that's why the, "just reach out to someone!" platitudes are so prelevant, because to these people, they always have confidants that they can confide in. They can't fathom being totally alone or unable to cope through distractions.
Those who haven't been through it simply can't understand. It's as if we are living in an alien universe compared to them. It sounds like crazy talk because they've never had to contemplate what a fate worse than death would look like.