They mean the roughly 25 year tech sector run that's now culminating in the irrational exuberance of AI. There have been some hits already and the result of those is market cap consolidation of the largest companies. Not sure what the number is but the the 10 largest companies make up a huge percent of the entire S&P and most have extreme exposure to the same risks. The sector has been boosted by the NVIDIA circular financing as well but at some point there is a limit. Although they are angling for a pre-bailout with all the AI is going to kill humanity fear mongering. The only savior for the sector will be the government, the question is if the government steps in before or after an organic collapse.