Why don't people believe in mythological creatures?

Like, mermaids, dragons and fairy's, and other mythological creatures, why don't people believe in them? Just because there hasn't been an actual proper televised sighting of one, doesn't mean they exist. They probably do exist, but they have been hunted to near extinction, or are very good hiders. They are probably so shy, because they know that if they get seen, they'll get dissected or in a zoo or something. No one has properly seen Jesus, yet loads of people believe in him. So why isn't it the same for mythological creatures? By the way I meant no offence in my part about Jesus. I am a Christian and I respect and believe in Jesus.