This leads them to: a) sell low and/or stay out of the market due to fear b) buy high out of FOMO You are curently experiencing B. Lots of people hiding out in HISA are doing A. Those 7 stocks are by many measures really overpriced right now. While it's possible they will keep going up strongly, there is also a good chance their price will crash back to more normal levels, especially if it turns out that all the AI hype is not adding much to revenues/earnings. Anyway, there is always huge uncertainty with the future of the market, so it is prudent just to stay in your broad-market fund. Let the winners/losers rotate and just keep owning them all instead trying to time it.