Pseudo Desire?

Lately I've been thinking about the mechanisms that govern human desire. Why do we want what we want? Or, to be more specific, what makes us obsess about certain things when we know we'll never be able to have them? Is it simply a matter of them catching our eye, and then the knowledge that we will never be able to attain them working its magic through the power of reverse psychology? Or is it something deeper, something subconscious that interests us, keeps us--quite literally--captivated by the things we want? Or am I just trying to make myself feel better by painting the illusion of a bigger picture, by convincing myself that I'm not acting like a toddler who clamours for a toy simply because it's been taken away? But what if I am that toddler, but that toddler also wants the toy because of a deeper reason that transcends mere possessiveness? I know what you're thinking. If you'd have taken another toy, the toddler would've reacted in the same way. It's not the toy that matters; it's the fact that it's no longer there.

Is it true, then? Is our desire for certain things completely unrelated to the nature of said things? Do we want them because of the circumstances, because someone took them away or they're no longer there? Is that the reason we miss people? Not because we want them, but because we feel like they've been taken away? Darwinists would probably attribute that to some sort of evolutionary possessiveness that our ancestors needed in order to survive; what's mine is mine, don't take my shit--you get the gist.

But what if we really want what we want? What if the absence of the object of our desire is merely a reminder of how much we actually want it? You know, the whole you-don't-know-what-you-have-until-you-lose-it mindset. Can the same concept be applied to things we know we'll never have? Does knowing you can never attain something make you think of how much it would have meant to you if you were given the chance to actually have it? Think of every time you wanted to buy something but couldn't; didn't you think of all the awesome uses you would have put it to had you been able to purchase it? You might think, Yeah, but I know I wouldn't have put it to any of those uses had I actually bought it. But is that related to the question of whether or not your desire for it depended on it or on the circumstances? Couldn't the intervening factors of laziness and procrastination be to blame? Or is it all connected?

Is that why we expect things we know will never happen? I feel like "expect" isn't the proper term. The word I'm looking for is a cross between "expect", "hope", "want" and "wish". Do we really want these things to happen, or do we just enjoy the feeling of struggle? Does it all really come down to the concept illustrated by Miley Cyrus's song The Climb (you may laugh) that the journey is what really matters? Do we chase after things just because they will never happen? I know I'm basically asking the same question over and over in a myriad of different forms, but it's because they all lead to the same thing: Do I really want what I want (to have/happen), or do I feel like I want it just because I know I will never have it/it will never happen?