Is depression technically a selfish sin??

No, Depression is an illness and is no more a sin than having the flu or diabetes.

This will sound controversial but I believe that a depressive illness could follow the act of sin. The loss of control in doing right to your fellow man and indeed stepping away from the commandments set before all men to pursue a clean and positive life escalates that fall that takes you out of the light into the darkness. At that point another form of thinking is allowed to flourish and the fundamentals of severe or chronic mental illness begins to manifest itself in all kinds of ways, feelings and emotions. It is clearly stated in scripture that the battle between good and evil is the battle for the mind. There is no doubt that sin is an avenue into that cauldron of the mind and the most chronic pain imaginable.

Depression isn't a sin, neighbor, it's an affliction. I've had chronic depression my whole adult life and I'm not the least bit selfish. Don't use your infirmities as an excuse for your character, or lack thereof.

depression is all in your thinking if you are feeling depressed then you are thinking depressed thoughts so change your thinking and only think good thought and your depression will go away, same with feeling jelous.

no, depression is a symptom of sin, yes, but not in all matters because there is more than one kind of depression and many kinds of causes

Only if you are an imbecile