If you touch that stove, it will burn you. If you don't behave sensibly around the road, you might get hit by a car. If you break the law, you might get arrested. These are a few likely or guaranteed consequences of poor choices we might make in our lives. As adults, we all know this, and very few of us would object to teaching these facts to kids. I remember distinctly seeing the horrifying sight of burned corpses of children who played near pylons. These images were traumatising, and I definitely wouldn't want to see those videos again, but I would certainly have preferred seeing them to being blissfully ignorant of just how dangerous our world is and therefore unequipped to deal with it.
Many atheists today claim Hell is just a scare tactic designed to bully people into accepting Christianity, but this is circular reasoning. It is based on the assumption, not the knowledge, that Christianity isn't true and Hell is not a real place. When Jesus preached about Hell, He wasn't just preaching something He made up on the spot. He knew that Hell is a real place where, at the end of our Earthly lives, we will almost certainly end up. It is the final destination for all sinners, because the Holy nature of God is such that He cannot allow sin to go permanently unpunished.
But while Hell is a reality, Jesus had the answer, too. He, Himself, was worthy to take our just punishment upon Himself. By His death on the cross, anyone on the Earth, including you, can escape the inevitability of Hell just by repenting of sin and turning to Him in faith.
Ray Comfort once gave the analogy of a man drowning in the ocean. The man is wearing a belt of precious gold, which represents sin, and it's weighing him down. Christians are like a man who was also drowning, wearing a belt of gold, but threw off the belt and climbed into the lifeboat, and are warning the atheist to do the same. Because sin is so precious to mankind, we tend to prefer the "gold belt". Objectively, it's better to survive without the gold, but in the atheist's mind, they'd rather keep the gold and try to swim for it. Denying the reality of Hell is a temporary comfort, but ultimately it is fruitless.