That's a shame she doesn't understand...I didn't read everyone's replies so maybe someone already said this, but yeah, I think messing with the brain is a lot more risky than changing the body. Who knows what damage could occur as a result?
As for her question as to why people need to physically transition, as opposed to just be comfortable with who they are...honestly, I've been on hormones for almost 3 years now and I can say, without question, there is a very physical and chemical aspect to gender dysphoria. Before HRT, and in the times where I have been unable to access HRT, there was something undoubtedly physically wrong with me. I don't know how to put it into words, but something was off balance, and it affected my mood, my energy levels, just my overall sense of well-being was hugely damaged. I could have been the hottest dude, totally stealth, accepted by everyone as 100% male but without T inside me I would not be OK. So imo there is definitely something chemical that contributes to dysphoria.