They are fearless at that age. Would you risk that and as an adult you know that the risk is small. I am not sure that the kids know the level of risk or even consider the "odds". They just have a "belief" without the re-assurance of knowledge.
Youth knows no fear. They are bullet proof, you know. Some things you don't do after 50-this is one of them. The other is thinking you can do the split like you did at 16. The look on Granny's face says it all.