radioactivewhale, some have said on any given day in the US HFT can account for 70% of volume. You are so correct and combined with the very insightful and forward thinking post of Gwaihir above it reveals what can only be described as a scary future.
The authorities are either so fixated on short term positives (increased turnover) or so blinded by the people who lobby about regulating these beasts that the market will end up no longer serving the purpose it was designed for. And in the long run we will all suffer imo!