"What does it matter how someone identifies?"
Doesn't matter at all until they want tax-payer funded treatments, start trying to get into pre-teen girls' locker rooms, compete in women's sports, insist that 'men' can become pregnant, and disrupt women-only spaces (along with the absolute nonsense of 'trans women are real women'.)
And don't get me started on the 'nonbinary' folks and drag queens.
The problem with kids these days is they can't tell the difference between gender, personality and sexual fetish.