Dylan McWilliams doesn’t believe that old saw about lightning never striking twice. Not after he was attacked by a shark Thursday in the waters of Kauai less than a year after he was mauled and dragged by a black bear in the wilds of Colorado. And certainly not after he was bitten by a rattlesnake in Utah a little over three years ago. What is it about this guy that draws dangerous predators with sharp teeth? “I don’t know,” the visitor from Grand Junction, Colo., said Friday.