I've been thinking that recently too, although it's possible that I'm only now paying attention because I've finally become someone who has enough money to ask "what do I do with my surplus money?". That's not something I had to concern myself with 10 or 20 years ago.
Some folks will rightly point out that there have always been fads, but things feel quite outlandish these days with GME/Wallstreetbets, Bitcoin, NFTs, SPACs. The stock market as a whole has done well over the past year, but it's been outpaced by stuff that feels like people counting on a greater fool. But then here I am on the sidelines, avoiding the riskiest stuff, and of course a bit envious of their returns, so who's really the fool? Shrug