Is There Any Downside to Index Funds?

The markets to day seem wegh more efficient than they ever have in history. But the broad attack from largely active managers who are seeing their profit margins squeezed, complaining about this, i find extremely unconvincing. I'm not an efficient market zealot but it's a useful mental model for how markets do work. And humans do dumb stuff all the day. We'll dumb stuff like gamestop come or sub prime crisis happene all the time. In the long run, does that change the fundamental issue that marks a really heartbeat for the vast majority of people? No, not really.