Why were there so many sightings of Loch Ness Monster and BigFoot?

I'm not sure who out there believes that the Loch Ness Monster and BigFoot is real or not real. Though, I had to do a report on this subject...and there are sites that say there were more than over 100 sightings of the Loch Ness monster and BigFoot. (and other similar monsters.) Why is that? I don't believe that they are real, but how come so many people claimed to see the Loch Ness Monster or BigFoot? Even if they were real, wouldn't they be discovered by now?