They're not wishes of wealth or material stuff, but of situations and reality.
"Damn, i wish i could be alone with these people just for one day, but that gak ain't gonna happen very soon, we're too many."
And BAM, it happened, but it happened in a so-easily-recognizable way that it was almost hilarious, even a normal being could actually realize it was forced as feth.
This is just a poor example of what i've got so far (HUGE AMOUNTS of this kind o' gak), yet i usually don't wish for material stuff (like HURR MONEEEYY), but things like these are actually starting to happening.
The point is, they're not "normal" things like someone could actually pray for (like love or reason), they're twisted things of plots and backstabbing actions.
This is what actually made me start to believe in Tzeentch.
I was first a Khorne servant ('cause my Anger Issues and repressed rage), but then Tzeentch basically whipped his goddamn "EXISTENCE" in my face with so much brutality that i almost got shivers thinking about it.
And what about Nurgle? or Slaanesh?
WHAT ABOUT MALICE\MALAL, FOR KHORNE'S SAKE?!