> And the index funds followed right along. Perhaps index funds, by blindly following market trends, amplify bad actors' ability to distort the market.

Well of course index funds follow market trends. How is that at all surprising? They are literally index funds.

The point is that blindly following market trends, when the market is being manipulated, is not a good thing. Yet it's a core feature of index funds. It's a big potential downside of index funds.

In general, the standard retirement investing advice these days is to invest in a portfolio of index funds -- don't bother with active funds, and don't pick individual stocks! People who take that advice probably expect that they are investing in a slice of ownership in companies that will grow over time, not that they are enabling/following along with market manipulation and being suckered into buying overvalued assets. It makes index funds a lot less attractive as a safe investment for normal people.

I mean, competitive, publicly traded markets like the stocks underling SPY are not manipulated long-term.

Index fund investors are not being "suckered." People who get convinced that they can time the market or pay someone else to time the market are the ones who are "suckered."

> index funds a lot less attractive as a safe investment for normal people

As long as you aren't day trading, I don't see why this volatility ought to even be a concern for normal people. I'm not buying/selling based on 5% shifts in the market on a day-to-day basis.