Closet_Gamer
Thinks s/he gets paid by the post
It's a self-repairing process but the concern is based on the false premise that there is a risk the price discovery will stop happening. It won't, because passive investors' activity will never dominate trading.
If price discovery does stop happening though, then the other side of that coin is that mispricing is occurring. (Blind, ignorant, buyers, etc.) The whole premise of stock picking is to take advantage of mispricing, so the long knives will be right there when needed. Ben Graham will be back in vogue.
This.
Passive investing is taking a free ride on the price discovery process. To the extent price discover weakens, there will be excess returns available and people will move in to capture them. I don't know the math, but I suspect that if even 1 or 2% of trades were "active", the market would remain pretty efficient and if not would quickly rebound back to the point of price efficiency.
The fact that we still see big moves in individual stocks in response to news (good or bad) and that other specific stock's prices hold based on sentiment about long term potential tells me that price discovery is alive and well.
Finally, while I don't agree with the OP, I do appreciate the creation of a fun thread!