What's the worst that can happen?
Well, kids who are coming to terms with their feelings of same-sex attraction in a homophobic world, or of being autistic and not fitting in or understanding social cues such as society's enforcing of gender stereotypes, are introduced to gender identity and think they have the answer to all their problems.
Without it, they have a good chance of growing up to be well adjusted lesbian, gay or autistic adults with a chance to have fulfilling relationships and start a family, should they want to.
But with gender ideology, the risk is they decide they're trans, get given blockers before puberty kicks in, then go on to cross sex hormones like 99-100% of other DC on blockers, and never develop into a sexually functional adult.
They grow up to be medicalised, sterile and unable to have a sexual relationship with another person as they have no sexual feelings or function. They also have a host of other side effects including brittle bones. They may have a limited life span.
Go spend some time listening to detranstioners if you think I'm making this shit up.