I find fans dont do anything when its anything over slightly hot. Certainly when its 25 degrees plus they do naff all. Ive got my fan on right now, its doing its job but its only about 18 degrees just humid.
As for being an unnecessary luxury i disagree, if it improves your comfort and helps you sleep what can be more important than than that. We have it in work vans to make the hot days more bearable its the same thing.
But who cares, let people roll around in bed sweating their nuts off with a fan blowing hot air on them if it makes them happy.