I think "not passing" is too broad of a term for the sake of this discussion. I see two distinct not passing camps. One is the the FTW, If I say I feel like a woman then it is your problem if you cannot see me as one (even though I seemingly make absolutely no effort to). Then there is the I am glad to finally be happy in my skin camp. Those that do try to pass, try to conform to societies norms, yet know they really don't. Nevertheless they are finally happy with themselves realising all that.
There is a member of my TG group my heart absolutely goes out to. This poor soul, much like me tried their best to live up to their birth role. But now after realizing the truth about himself feels that there is no point to his life. No way can he ever pass. No way can he have a chance to grab the brass ring of happiness, much less joy. Just doomed to a miserable tortured existence. Unless, of course, he drinks himself to death, or use a more direct method.
So one can argue we place too much emphasis on passing as being critical for sucess. A position I well understand having twice in my 20's stopped my experiments on transitioning. Due in large part to me not wanting to voluntarily go into a life being a target of ridicule after barely escaping one that was. At an ugly 6ft tall, big frog hands, super extra large feet, super-sized super orbital ridges, deep voice, and balding I was far from an ideal candidate for transition.
It takes a lot of work and growth to get to the point where you finally reach a place where you allow yourself to put your own happiness above someone elses or the rest of societies. It may not be a perfect or ideal life, but neither was the one you were leading. It's every individual's perogative to do that cost-benifit analysis.
I put myself sort of into the "I know I ultimately don't.. but" camp. I finally found happiness and joy in my life. Happy being me. Finally glad to be part of the body I inhabit. In an area of 5'4"250 lb women I know I stand out at 6ft and 150 lbs. I always try to present as unabiguously female as possible. No doubt it helps.