and well, for example the positive mental effects of hrt can be reasonably well explained by social/psychological factors. the confidence boost, zhe certainty that things are getting better, the knowledge that change is finally comming etc. are a reasonable explanation too.

Not in my experience, no. Because when I started testosterone, I planned to just stay on long enough for my voice to drop. I didn't want to have to do weekly injections for the rest of my life, so I fully planned to go off T after a few months. After a little while I decided I'd stay on T at least until I had a hysterectomy so that I could avoid dealing with a period ever again. But after my hysterectomy, I did indeed go off T, for approximately 4 months. I wanted to give it a good go, so I stayed off until I hadn't had any hot flashes for several weeks, at which point I was quite sure that my endocrine system had stabilized. I felt awful. Just, so fucking bad. It's hard to explain how much worse life was without T. I wish I still had access to the hexbear account I had at that point so I could link you some of my posts from that time. It affected everything, my mood, my energy levels, my appetite, my orgasms. Everything was just muted, I was constantly on the verge of tears, I couldn't stop clenching my jaw. And you know what? I recognized this feeling. It felt like I was back in middle school. It felt the same as the first time my system flooded with estrogen.

So sure, we could do a study where we take trans people off their hormones and see how miserable they are. Sure, we could do that, and I think it would be pretty dang revealing, but I don't think we should, because I'd never wish that misery on anyone else.