Comment by matwood
And he's right (and the sources he points out), that some bubbles are good. They end up being a way to pull in a large amount of capital to build out something completely new, but still unsure where the future will lead.
A speculative example could be AI ends up failing and crashing out, but not until we build out huge DCs and power generation that is used on the next valuable idea that wouldn't be possible w/o the DCs and power generation already existing.
Huge DCs and Power Generation might be useful, long-lasting infrastructure, however, the racks full of GPUs and TPUs will depreciate rather quickly.