Kids are never offered "life changing surgeries". This doesn't happen. Evidence very much suggests being trans is a genuine neurological condition that we are born with.
Brains are not necessarily binary.
We understand some of the causes.
"Risk" of being born trans seems to be partly genetic.
The American Academy of Pediatrics is on our side.
Adults don't regret surgery. And another study on the same.
Additionally, getting a diagnosis is a long process (and it's not guaranteed that you'll get one), and then actually getting treatment takes even more time (also not guaranteed).
EDIT: I can't read what the transphobe is saying anymore as they have rightly been banned from the server I'm on. Detransitioning is uncommon, but of course perfectly valid. Typically people detransition because of transphobia or for economic reasons. Have some additional links:
Rates of detransition are low, and they are only very rarely permanent and caused by true regret.
GenderGP links multiple studies saying essentially the same thing.
This one mentions detransition rates of 13%, but again mostly to escape stigma.
They would have known this if they bothered to open the surgery regret rate studies I linked them (but we both know studies won't change their mind). For the lazy it's less than 1% for both transmascs and transfems.