 We should fear snakes, and so adults want us to fear snakes when we're young so that we don't get a hold of something that we had not to. Because, of course, kids will grab a hold of anything. And it's sort of healthy to have at least some level of fear of things that could hurt us, especially if we can't tell the difference between the ones that might hurt us bad and the ones that might be overall beneficial and might not hurt us at all.