The minds of gods are not for mortals to know or to judge. Accept that Tzeentch has a place for all of us in his grand scheme, and be happy in the part you have to play.

Do not ask which creature screams in the night
Do not ask which creature screams in the night,
Do not question who waits for you in the shadow.
It is my cry that wakes you in the night,
And my body that crouches in the shadow.
I am Tzeentch and you are the puppet
That dances to my tune.