Many, many people are not looking at PE at all. They are buying into momentum alone, or just buying because it's in the news a lot.
AI may change the world, but it's currently a bubble figuring out how to inflate.
It's implied in the above is that it's for anyone paying attention to E. Practically everyone understands that for every conceivable reason there is a buyer buying for that reason somewhere.
You may think it's a bubble. It's not obviously a bubble to anyone who understands the current capabilities and how locked in nvidia is with their gpus and cuda. It might end up being expensive in retrospect. It might not.
Whenever a PE looks expensive people are expecting very large increases in E. They aren't just trying to buy expensive stuff.