You seem awfully sure about that. How do you know? How do they know?
On the basis that gender dysphoria most likely has a physical cause and changing gender stereotypes wouldn't affect that, yes.
Gender dysphoria is similar to other dysphoric conditions, and have a similar, physical, root cause. This is based on twin studies and genetics. See this paper and this one.
There are also a large number of papers on the development of gender identity which appear to support this view. In many studies, the outcome for gender non-conforming children (those who are happy with their body but don't want to follow gender stereotypes), and gender dysphoric children is different. In other words, there is a distinction between "wishing" and "believing" as I mentioned above.
Children with gender dysphoria seem to keep knowing their sex is wrong; GNC kids are more likely to accept their sex and simply be GNC.
None of this speaks as to whether gender dysphoric people are women or not. If you are GC, they aren't; 4th wave feminists, most medical professionals, and human rights bodies would say they are.