I kind of agree with your underlying premise, but when I invest in a mutual fund / ETF, isn't that a giant investor that might be affected by HFT? And if that was costing the fund money, wouldn't that affect me (without me seeing it directly)?
Assuming that hft forms didn't drive other prices down. In particular the costs to trade (in the form of the spread, fees & execution costs) hadn't been decimated by hft firms.
