Believable theories on Cross-dressing

[Marla S]

In fact there are dozens of botched circumcisions on male babies all around the world that have resulted in baby boys being turned into girls and none of them ended up like the David Reimer case. They accepted their new gender without the issues that arose in the Reimer case. Indeed there was a boy who lived in an adjacent town to where Reimer lived who also had his penis removed as a baby and is now a happily married woman.

I am not an expert here, but when I read the bold parts, I get mixed feelings.
Given that there is something like a core gender identity (flexibel or not), what do we know about the issues and happiness.
Not every TG is a potential suicide (survival instinct is probably the strongest instinct we have and it is likely that it covers other needs), happiness is in the eye of the beholder. Personally I thought I'd know what happiness is (actually I was a bit disappointed), but after I was able to accept myself another stage was ignited.

What do we know about all these people that are not happy with their life ?
Is it only the job, the money, trouble with wife/hubby and family ? Or might there be some that try desperately to adjust to the gender norms, but fail and don't even know why.
(We all here know that thinking about the own identity is a very difficult and exhausting subject which requires some intellectual potential not to get lost. Not everybody is gifted this way, and some that are might "find" other ways to deal with it.)

Does it need clothes to be TG ?