If gender is a socially constructed thing, like there's a 'caricature' of a man, then why do we still consider people 'men' who don't correspond at all to the caricature of a man? And then I doubly don't understand how you can change your gender by making a decision about it.
In a sense, yes? As in, I'm down with the path of least resistance. If someone is distraught that they have an arm, and cutting off the arm leaves them less distraught and there's no better way to fix the dysphoria, then whatever, go cut off the arm. Whatever works, do it!