I don't know the lore all that well, so I'll start this question by first explaining my understanding of events that lead me to the question in the first place:
So, as far as I understand, the High Elves were dependent on the Sunwell throughout the RTS games until Arthas destroyed it. Then, the High Elves (soon renamed the Blood Elves) went through withdrawal due to some sort of a magic addiction that they now struggled to sate. They started to feed on alternate forms of magic, occasionally the fel, leading to corruptions such as their green eyes and things of that nature. They drained mana from living things, like those mana wyrms.
So here's my question...
What about the High Elves that never joined the Blood Elves of Quel'thalas? The High Elves that remained with the Alliance? The Silver Covenant, the Quel'danis Lodge, all the random High Elves wayfarers we see. Were they not equally affected by the destruction of the Sunwell?
The Blood Elves found alternate forms of magic to feed on, but does this then apply to the High Elves of the Alliance too? Were there those green demonic pillars hidden somewhere that they fed on, like the green pylons in Silvermoon City? If not, how did they sate the hunger?