If that was all they were doing, that'd be fine. But read the book.
Some exchanges have 150 types of orders that are mostly undocumented and unknown to most regular players, created specifically so that HFT can not do what they publicly appear to be doing, or take incentives without providing liquidity, etc. The public price that everybody seems is outdated compared to the private prices that HFTers see, so they can risklessly front-run people because they already know if a price has dropped or rise, etc. All that stuff isn't just fast market-making.
The "public price that everyone else sees" is the same price as the HFTs see. These are available on the direct feeds from the various exchanges, and there's no discrimination against non-HFTs. Anyone who pays for it can get it. It's an equivalent advantage to having a Bloomberg - more data, faster.
Some exchanges have 150 types of orders that are mostly undocumented and unknown to most regular players, created specifically so that HFT can not do what they publicly appear to be doing, or take incentives without providing liquidity, etc. The public price that everybody seems is outdated compared to the private prices that HFTers see, so they can risklessly front-run people because they already know if a price has dropped or rise, etc. All that stuff isn't just fast market-making.