When it comes to saying that "something is unrealistic", I look at it as though I'd rather have low expectations and be pleasantly surprised, instead of having high expectations and being unnecessarily disappointed.
If you compare this "unicorn hunting" to "playing the lottery", that ought to put it into perspective. It is "unrealistic" to "expect" to win the lottery, but you will definitely NOT win if you don't play.
But, it's all about perspective, and how folks choose to evaluate the input they are given. Ultimately, we do what we do and whatever happens, happens.