The problem is more likely that companies like WD doesn't know if this will be a bubble or not. Currently they can milk the market by raising their prices and just rely on their current production facilities, maybe expand a little. If there's going to be crash, then it's better to have raised the price, even if just temporarily, rather than being left standing with excessive production capacity.

If it's long term, it would be better to be the front runner on additional capacity, but that's assuming continuous growth. If it all comes down, or even just plateaus, it's better to simply raise prices.