Yeti, Bigfoot, the Loch Ness monster - all just fun, figments of people's imagination and folklore
I'm not going to completely say that I dogmatically believe in the Yeti. Sure, there's interesting 'evidence' that the Yeti may exist, just as there's compelling evidence against it's existence. Simply dismissing the possible existence of such creatures, however, seems - if I may say so respectfully - somewhat uneducated on the subject.
There are a few reasons that I can't simply dismiss the theories that such animals may exits. The astounding body of sightings of bizarre animals in the sea and Native American legends pertaining to what appears to be a Bigfoot-like creature are only a few. I find it difficult to simply dismiss a very
large body of relatively similar sightings as a collective hallucination. (Especially when, in the case of 'sea serpents,' sightings may span hundreds of years and fall mostly into discernible classes.)
Of course, I'm not completely arguing in the existence of Loch Ness, Bigfoot, or Yeti. I personally believe that there's something in the legends and sightings, but I also completely understand an educated opinion against.
Dismissing the possibility of there being animals undiscovered by science is an excellent way to never make new discoveries. It's also unrealistic. Despite what some say so pugnaciously, there is
evidence out there for the existence of these creatures. Admittedly some is scant or even blatantly fallacious or ridiculous, but there is also some pretty compelling arguments.
Don't for get that the Coelacanth was believed to be extinct until it's discovery in 1938 - A true Lazarus Taxon.