Human nature.

Tell a child NOT to touch the red button and that red button becomes the most irresistable item in the world. Tell the child they can play with it as much as they want they see it for what it is, just a red button.

When we cant have something it becomes something else, when we have it we satisfy the urge but are left with the harsh reality of what it REALLY is.

I go through this all the time, drives me nuts even though I see it.