No one is trying to give you a hard time, they are just trying to give you perspective.
We've all just seen lots of Fats come and go for sale over the years. The site requires listing a price if you are selling, but you could do a simple WIW thread if you hadn't been flogging it for sale.
There are several Fats on eBay that have been sitting there for years at outrageous prices. Fat City Cycles had a number of models and prices vary considerably based on condition and what components are fitted, whether it has the original fork, rarity, etc etc.
Yes, it is a great bike and was not cheap when you bought it. That said, it was the lowest range Fat City bike. A Yo Eddy is generally worth a good deal more. Just to give you some ball parks figures for Monster Fats:
I've bought Monsters in much better condition than yours for $350-$800, both on this site, craigslist, and via eBay. I've seen them sell for as much as $1,000 for the frame/fork only, but that was for an exceedingly fine example in a rare color that might as well been new in terms of condition. In contrast, your bike looks like it has seen some good use.
Ultimately, if you really want to know what the market will bear, clean it up, take some nicer pics, and let it go on eBay. My feeling is that you would be lucky to get about a fourth of what you are asking here, but you don't have to take my word for it.