Yep. Keep in mind that investing in index funds was a successful strategy during a period when it was not so commonplace. When it becomes the norm the whole foundation of why it was successful changes.

You actually have to have people analysing companies and stocks, ie actively trading based on fundamentals, for it to work. Index investing is piggybacking in that. But when it becomes the driving force the market loses its ability to pick winners and gets dominated by momentum, and can be taken advantage of