Why doesn't the Loch Ness Monster exist?

People tend not to believe in the Loch Ness Monster because nobody has produced credible proof in real life that it exists. Sure, there have been photographs of body parts sticking up out of the sea, but there is no telling what creatures they belong to. Other photos show a blurry creature, but the photos are too bad to authenticate or even make out what is in them. So therefore, in the minds of many, it's not real.