It's the "eBay Syndrome". People see a pristine KO sell for ten grand on ebay and they think that translates to the entire line of all sohc4's of all years, and suddenly think they're sitting on a gold mine in their neglected, rusty, non-running K6 that's leaning against the side of their house.
Also, a lot of people seem to think that they should get paid for their time when selling their bike. They think the time they spent working on a bike somehow increases its value to others, when in reality the only thing that matters is the end product and the value/necessity of the parts used. I don't care if you spent two years bringing the bike back to life and on the road. If I can get another bike just like it, in similar condition, that was stored properly and didn't require a rebuild/restore for half of what you're asking for yours, then I'm not paying your asking price.