Edit: changed the word sadness to depression.
> Quantifying that nothing in someones life (or their past) is causing them sadness
I didn't say sadness, I said depression. They are not the same.
> This charade
Wow.
I'll give you the benefit of the doubt and assume you've never experienced depression, and don't know anyone with it.
If that should change you'll quickly realize just how mistaken you were, and you'll feel bad for ever saying things like this.
To put it in context: It's like telling someone blind who still has physical eyes "You can see, stop pretending."
I don't agree or like that statement. You're alluding to something approaching a faith-based illness, whereby you fight against anyone looking for causes, insisting there is no cause. "It just is".
But that doesn't fit with what we know about how stuff works in this universe. If the brain is not functioning as it should regardless of good life circumstances including health, family, lifestyle, then something is definitely causing that malfunction. Don't shoot down someone looking for causes to a problem.
You are under the common delusion that depression is caused by something in a person's life/environment.
This is NOT TRUE!
Depression is often caused by nothing whatsoever. Someone is simply depressed with absolutely no reason at all.
Depression that is caused by something is not strictly depression, it is a semi-normal response to difficultly and people will automatically fight to try to make life better - you don't have to tell them to do that. (The problem comes when they aren't able, or don't know how, to fix things.)
Depression is caused by nothing. The brain is just not working right. You just have to wait it out, learn coping methods, sometimes drugs, or sometimes you may be able to do a physical activity that gets the brain working right again.
If you can internalize that depression is not caused by circumstance you will go a long way toward understanding people with depression.