A bubble doesn’t mean a technology is useless. It just means it’s overvalued
In the last 30 years, we’ve had multiple bubbles in the tech industry. Every one of them was backed by real stuff that we still use today. They were still bubbles and a ton of people were hurt when they popped.
I know. I'm saying that overall I don't believe it's that overvalued.
Specific things may be overvalued. I suspect data center real estate is a bubble, for instance.
The railway bubble and the optical fiber bubble left the world with lots of railways and optical fibers. Once their original owners went bankrupt, the assets themselves were quite useful and changed the world.
The cryptocurrency bubble, however, didn't. Not really. At best you can use it to buy drugs. Some of the GPUs may have been repurposed for AI, but not enough to make a dent in AI, and the AI reesarchers who kicked off the AI bubble were having to buy their GPUs for high prices to compete with the miners, not low prices after they went bust, so we can't even say miners helped kick it off.