US economy has been running on bubbles for decades, and using bubbles to fuel innovation and growth. It has survived telecom bubble, housing bubble, bubble in the oil sector for multiple times (how do you think fracking came to be?) etc. This is just the start of the AI bubble because its innovations have yet to have a broad-based impact on the economy. Once AI becomes commonplace in aiding in everything we do, that's when valuations will look "normal".