I've ended up in a few conversations recently where someone has basically said to me "I don't mind trans people I just don't get it." My response is along the line of "the body fucks up and has birth defects all the time, some people are born with a cleft lip or an extra finger or shrunken limb and some people are born with the wrong genitals and hormones. Theres no real difference and you certainly would support a blind person getting their eyes fixed so of course you should support transpeople getting their genitals fixed." So far for most of the people I've talked too this has been like a light bulb going on.
However I don't currently have any irl trans friends to bounce this off of and I want to make sure I'm not being an idiot and framing it in an offensive way or missing something I should really be adding to the conversation.
Body dysmorphia is entirely different from gender dysphoria (or gender incongruence, as it is known nowadays). Trans people can have both at the same time, but there are working treatments for body dysmorphia in anorectic people that would be outright conversion therapy and totally unworkable in dysphoric trans people. If somebody has dysphoria, the cure for that is transitioning. That works reliably with a completely outstanding success rate. You can't tell an anorectic person who can't view her body realistically anmore to just lose some weight, but in trans people, just taking hormones works perfectly fine.
Also dysphoria isnt an entirely physical thing, either, there's a lot of dysphoria that relates to social phenomena - having to wear clothes that do not align with how you want to present your gender, being adressed with the wrong name and pronouns, being forced to use the wrong bathroom / locker etc. are all common causes of dysphoria.
But yes, being trans does not require being dysphoric and if we focus the conversation on dysphoria, we automatically take validity away from the trans people that do not seek to medically transition, or whose transition goals do not meet a cis and binary norm of how bodies are supposed to look, and it introduces problems such as having to pass. There's basically an entire power structure in place that is not touched by the "trans people are just born in the wrong body" narrative and it remains in place and extremely harmful because this is the way we still commonly present the issue.