I don't consider my situation to really be one of extreme gender disappointment.
Someone touched on it before and I think calling it 'disappointment' does not make it easier to understand. It is grief. Just like if you want another baby or any baby and you cannot have one at all due to medical/financial issues. Except in this case it is not 'a' baby it is a boy or a girl baby.
Maybe this is just because early in life we may have an idea of what life will be like in x amount of years. And in that idea/dream we may see a boy or a girl etc etc. It is an idea you grew up with for years. It is precious to you. And if it can't happen or does not happen you mourn the loss. And there will always feel like something is missing.
I am not trying to force you to change your mind here. It is always hard to understand unless you go through it. I thought maybe it might help you see why someone makes that choice - whether it be right or wrong I cannot say because I do not know.