Additional evidence that HFTers are not stealing from speculative investors: Anyone can start a market. If HFTers were stealing pennies someone would have come along and started a market that banned HFTers (or changed the rules to otherwise get rid of them). Then all of the speculative investors would use this market instead since they could be assured that no one was siphoning off pennies on every trade. Eventually…
There are market centers that prohibit high frequency traders. Reg NMS requires any center that disseminates quotes to prohibit trading through the NBBO (best price at any point in time across all exchanges). So these market centers must be dark pools, not exchanges nor ECNs.
These centers represent a small and shrinking amount of trading volumes. Nonetheless, they exist.