I can't say there's a definitive reason as to why there are such problems amongst transgenders and neither can you since there is no conclusive evidence, only hypothesis and theory but there is a big belief in psychologists that it's not due to their treatment in society but more due to the feeling of gender dysphoria not being treated as a problem but being celebrated so they never get the therapy they need but instead just go through with gender altering operations before analysing properly their mental health before hand which only worsens the problem. The truth is we don't know why there are such problems within the transgender community but we can't risk the security of a country because of these problems until we conduct more research and find the real reasons, only then should we allow them to serve the military, when we know more