You get the Lacan’s points. Fantasies have to be unrealistic because the moment the second that you get what you seek you don’t, you can’t want it anymore. In order to continue to exist, desire must have its objects perpetually absent. It’s not the “it” that you want; it’s the fantasy of it. So desire supports crazy fantasies.
This is what Pas means when we say we are only truly happy when daydreaming about future happening. Or why we say “the hunt is sweeter than the kill.” or “be careful what you wish for.” not because you’ll get it, because you do not to want it once you do.
So the lesson of The Lacan is “living by your wants will never make you happy.” what means to be fully human is to destrive to live by ideas and ideals. And not measure your life by what you tame in turns by desires but those small moments: so integrity, compassion, rationality, even so sacrifices