Inflation is heading up, jobs are becoming more scarce. The war in Iran is costing a lot. The federal reserve is now talking about when they are going to raise interest rates, instead of when they are going to lower them.
Plus the incredibly optimistic valuations they are talking up for the big AI company IPOs. If they didn't think we were nearing the top of the bubble, they wouldn't all be planning their IPOs at the same time. It's a race to see who can cash out first before it pops.
It feels similar to 2007-2008. People were talking about a bubble. But nobody wants to jump off the train too early and lose out on the big profits just before the end.