Post-purchase rationalization, also known as Buyer's Stockholm Syndrome, is a cognitive bias whereby someone who has purchased an expensive product or service overlooks any faults or defects in order to justify their purchase. It is a special case of choice-supportive bias.
Expensive purchases often involve a lot of careful research and deliberation, and many consumers will often refuse to admit that their decision was made in poor judgment. Many purchasing decisions are made emotionally, based on factors such as brand-loyalty and advertising, and so are often rationalized retrospectively in an attempt to justify the choice.
http://en.wikipedia.org/wiki/Post-purchase_rationalization
Then you can also take post-sell syndrome, we have all been there, no matter what u do, there will allways be something clouding your judgement.
I have <10 btc from <200$, and i dont see this going anywhere else but down, still, i didnt yet sell, only because market is so unpredictable, that common sence rarely gets you far.
cheers