It's not an easy thing. That's why using puberty blockers for a while sounds like a good way to buy some time to make this decision. I think kids are more likely to pretend to be straight than to pretend to be gay. There are people who have regretted transitioning, just as there are people who regret all kinds of decisions, from becoming a parent to getting a tattoo to getting intimate piercings. I would say, however, that if a child is consistently saying they want to transition from the time they're 4 to early teens, we should listen to them. Trans kids who are NOT supported are at very high risk of suicide.