Is depression extreme selfishness?

No. Depression is a neurobiologic disorder and nothing to do with being selfish. Please seek help so you do not feel this way. Good luck.
No. I think that it is very important not to judge others, despite their condition or handicap. Don't you? If you look at someone as just being selfish, that can lead to resentment. Please try snd understand that physical and mental illnesses are nobodies fault. Rather, we are all human and have human problems.