If a Monero mining bubble happened, the second it became extremely profitable, some ass that works at Dell or somewhere would turn his entire building into an after hours mining farm and completely destroy the marginal cost structure.
You are completely confused about the scale of things. Even at the current price, mining is the equivalent of 70K high end desktops. A building at Dell, etc. would be a drop in the bucket, even more so in a bubble environment when mining would get much, much bigger.
In fact if you look at power usage figures we're in the mid range of a Top 10 supercomputer now, which is a pretty good indication there is no centralized resource (or at least very few) that would overwhelm the network, especially during a bubble.