Don,
That is just another mystery that no one really has a good answer for. Possibly they convinced themselves that the site was "cursed".
It is really hard to imagine the mind set of those hunter/gatherers of 10,000 to 15,000 years ago. Why for example in the Americas did Clovis bury caches of very well made unused projectile points, were these an offering to some imagined deity? One of the most bizarre examples from our era comes from Irian Jaya/New Guinea of the "Cargo Cults". During WWII the natives saw the first airplanes and the wonders they carried. They proceded to build replicas of airplanes from sticks and vines in an attempt to attract more airplanes much as duck hunters put out decoys.
But getting back to Gobekli Tepe, the most significant aspect of the site is that a large labor force could be organized from scattered bands of hunter/gatherers. What motivation could compel such effort for a non food producing activity?
