But the thing is the same people who are open to talking about what they suffer from also have maintained friends, relationships, families, can maintain a job, is well-liked by people, are respected, can actually enjoy life, are happy about it and despite all this or any number of other positive things in their life are completely incapable of enjoying it to do their mental illness.

FTFY. Doesn't sound as bad when you look at it that way does it? Depression has nothing to do with how successful you are in academia, career, or socially. It can affect anyone. You say you don't have these things other people have. You seem to suggest that somehow that makes your depression more legitimate than others. Imagine this. You suffer from depression for years. That entire time you convince yourself that it is simply due to your position in life. For example, no career, low income. You dream about how different things would be if you could just make some progress in life. Working hard at it every day. After years of failed attempts at many different career paths and educational ventures you finally complete a degree. Soon after you receive a job offer from a great company with good pay and even better benefits. You are finally achieving the things you have been chasing for nearly 2 decades. Then... You realize this depression you have have lived with the entire time(and truly believed was merely a side effect of you poor place in life) isn't going anywhere. You find yourself completely incapable of getting any enjoyment from you newly found success. The one thing you have strived for and thought would be the answer to all your problems has let you down... The realization that no matter how well you do, this dismal feeling is all you will ever know is crippling. You then sink lower mentally than you ever thought possible when you were still chasing success. How does that make this persons depression any less real than someone who has not found success?