Desire is a funny thing.
It drives us to do things we otherwise normally wouldn't, and blinds us to the reality of the situation in which we actually find ourselves. But, on closer inspection, most of the time desire leads us down the path of despair, setting us up for a fall. Consider these four possible outcomes if we pursue something we desire:
1. You obtain the object of your desire, and it turns out to be exactly what you hoped it would be.
The best-case scenario; your strife has not been in vain.
2. You obtain the object of your desire, and it turns out not to be what you hoped it would be.
Disillusionment sets in, else you lie and tell yourself that you were initially wrong. Maybe you'll be able to fool yourself; maybe not. Good luck.
3. You do not obtain the object of your desire, and it would've been exactly what you hoped it would be.
There's not much you can do about it now, and you could never be sure if it would've turned out like you hoped it would.
4. You do not obtain the object of your desire, but it wasn't what you were hoping it would be anyway.
Desire blinds you very well to this consequence, which is sometimes unjustly labelled "sour grapes."
Outcome 1 is what movies are made of. Options 2, 3 and 4 are what life presents to you much more often than 1. Yet, people still dream about Option 1; the de facto gamble, of course, is that you're trying to overcome 3:1 odds (although they're probably much, much worse in reality).
Now, I'm not saying desire is necessarily a bad thing: it drives us as humans to get better and smarter. But there's a right and a wrong place for it these days, and it spends most of its time in some fairly disreputable locales.
I guess Buddha was right after all.