HFTs can siphon away profits from the people actually doing good investing, but Not all HFT is created equal. There have been some pretty high profile instances where HFTs have increased market volatility and caused a "flash crash".
HFTs that trade at the microsecond scale probably aren't valuable to society.
That's all factually incorrect. The reason that HFT is valuable to society is exactly because it trades at the microsecond scale. That's how it provides the most liquidity.
Flash crash was transient and had no impact long term value. Neither does volatility.