Michael Burry has two main points against index funds: 1) large-scale passive investing has deteriorated the price discovery mechanism for index funds and 2) there's a liquidity risk because trillions of dollars are linked to stocks in index funds that only have hundreds of millions of trade volume. So if there's a cascading failure, as smarter money realizes the price is wrong and begins to exit, there will be no bu…
2) is only an issue if the underlying assets don't have any value or you need to sell at the worst possible moment. ETFs generally improve the liquidity of in a liquidity crisis.