wow story line

as we know the lich king "arthas" has doubt the light so the light left him
so this means the light leave anyone who doubted him does this mean the light have hidden motive ?
is the light actuality not good but evil ? and we know that the void "shadow" is fighting the light since the beginning so is it good .
and as the void controls the fel " the fel is void fragment " and the one who controls the legion is Sargeras "the dark titan" want to destroy the titans
what do they want from azeroth why the biggest fight is there ?

The Burning Legion (and the undead scourge, as a subgroup of the Burning Legion) was developed and sent by Sargeras to Azeroth in order to obtain Alterac Swiss cheese. Azeroth is the only place in the cosmos that the substance exists, and Sargeras seeks to obtain it all.

so the lich king betrayed the Legion to get it to him self only, and the light want it as will as the void so they fight once for all ? but why dont they all share is ? it is cheap