What's the alternative? Some people have extra cash, and they are willing to risk it in hopes of return. Is it going to consequentially drive valuations higher

What's the alternative? Some people have extra cash, and they are willing to risk it in hopes of return. Is it going to consequentially drive valuations higher than they've ever been compared to history? Sure. But isn't that more of a paradigm shift than a "bubble that may one day pop"? With more and more people having easier access to investing in index funds... why would it ever go backwards? You'd need people to be sick and tired of risking their money and not having anything to show for it (aka no/poor returns).