"I know trans people who, having struggled with dysphoria and terrible mental health, feel much more at peace after transition." This is so irrelevant! Surely the relevant thing is comparing -
1/ Individual's mental health and happiness before and after transition (as predicted by research / statistics!)
2/ Individual's mental health and happiness before and after mental health support which does not lead to transition (as predicted by research / statistics!)
3/ The cost to society of transition (both the costs of any medical intervention, plus the cost to society of dealing with people's cross-sex demands after they transition - the latter being an insanely high cost as this board proves daily)
4/ The cost to society of providing mental health support which does not lead to transition
I strongly suspect that whilst some trans people might benefit from transition that says precisely nothing about whether they would have been happier with proper mental health support instead of transition, and it says nothing about the ridiculously high cost to society of medial transition, and the relatively low cost to society of giving proper mental health support.