It’s not about doing what ever makes you happy. Even though that’s good. It’s about when people slip into depression, split up with the Mrs or generally going through a bad time they “go off Strava”.
There is no point in fretting about things over which you have no control. Others live their lives, and deal with situations as best they can. At worst, it will just drag you down and make your own life less happy, or make you into an angry person. If things happen to someone you know and you are able to help, that's great, but otherwise, you can't carry the world's problems on your own back, even the problems you know about, let alone the ones that you have no way of knowing about. You might extrapolate that they are making their rides private for the reasons you state, but there are probably a million and one other reasons for people doing such things and most of them are probably harmless.
Sometimes, you just need to stand back a bit and let things go. It is good to be concerned for others, but don't let this spoil your own enjoyment of the ride.
Speaking as a non Strava using person.