It's fairly obvious the suicide rate (and attempted suicide rate) is high because they believe they have the wrong body and that it is a great misfortune. Some are assisted in the delusion for a time that medical techniques can give them the body they believe they should have, but ultimately it can't and thus the depression returns worse than ever.
There are two and only two permanent solutions to the root cause:
1.) Stop believing oneself to be in the "wrong body" by some means.
2.) Actually get the right body by some means.
(1) may be possible, but of course no one but the dysphoric person could possibly know for sure. It's likely in my opinion that the dysphoria is encouraged and grew in many modern cases and thus would have been prevented entirely without so much "gender affirming" infrastructure. In the past self-acceptance may have been the best medicine for those with truly internal dysphoria.
(2) may be possible in 100 to 5000 years.