But to say it's okay to change gender and think you're of the other sex at such a young age is wrong. Thats the whole point of it.

They aren't changing sex. So what wrong?

Do you have evidence that this behaviour is healthy and dressing children up in the other genders clothes is actually beneficial for this child?

If you want evidence that supporting trans people leads to better outcomes yes. Not sure this specifically has been studied. But what's your logic in thinking it's harmful somehow?

It's not being talked about because it's "new" it's being talked about because an entirely different Pandora's box is opened regarding age, consent and sound mind.

Yes gender has continued to shift like it always has.

Kids are confused not idiots

I don't see what this kid is confused about, that's just a way of implying that them being whatever gender they want is invalid. Which you can think, bit it's just down to your assertion.