Personally I find snakes fascinating but I do know some people have an irrational fear of them. I accept that snake venom can be deadly, but the majority of snakes do not pose any threat.
I think it is a fear that originates in superstition and folklore, where snakes are bad omens or, as in the Garden of Eden, they represent evil. The serpent's forked tongue is also supposed to represent deception (as in "speaking with forked tongue").
There is also the myth that snakes are cold, slimy and nasty to touch, which I believe is entirely false. I have been lucky enough to see snakes in the wild, but so far I have not had the pleasure of handling one.