Jinn, I think you have some semantic flaws in your argument which have led you into arguing something different to what you originally believed. The problem appears to lie in your loose and vague uses of the words 'failure' and 'depressed'. Having firm convictions is great, but you need to know what you're actually convinced of.
'Failure' at what exactly? Unless you are, for example, an electronic component designed with a particular purpose, you cannot just 'fail', you have to fail
at something. So we can understand somebody who is non-specifically a 'failure' to be somebody who typically fails at whatever they intend or are intended to acheive.
'Depressed' is a term which you seem to define very specifically, but then apply very loosely. Your argument seems only to describe those who use depression as an excuse for failure, but by your wording you have treated everyone who is depressed as being in this group.
So, if you mean that everybody who suffers from depression is defined by their lack of success, then how do you explain Churchill, Kafka, Newton, Goethe, Schumann, Luther and Tolstoy? And
all these people? Whatever your opinions of these people, you cannot correctly brand them all as failures. Were they all in group 8? That's a fairly convenient get out for anybody who doesn't fit your argument. In fact if you use this excuse, you have closed yourself to refutation, which makes your post no better than preaching.
If you mean that people who are depressed have failed to be happy, then you haven't really said anything at all.
If you mean that people who use depression as an excuse for failure have still failed, or that there are some cases of depression which are best dealt with by 'pulling oneself together', then I agree, but this is not the same as saying 'If you are depressed you are a failure'.
I get the impression that you've got so hung up on defending the title of your thread, that you've lost track of what you were actually trying to say, but I'm quite prepared to accept that I have misunderstood if you are able to clarify what you mean.