I have trouble believing this assertion from the NYT: "[HFT] generate windfall profits on small and fleeting differences in prices at the expense of ordinary i

I have trouble believing this assertion from the NYT: "[HFT] generate windfall profits on small and fleeting differences in prices at the expense of ordinary investors and market stability" Considering this fact: "TABB Group estimates that US equity HFT revenues have declined from approximately $7.2 billion in 2009 to about $1.3 billion in 2014." Source: https://www.fas.org/sgp/crs/misc/R43608.pdf https://www.fas.org/sgp/crs/misc/R43608.pdf So the profit of the entire industry is a rounding error, but they're somehow fleecing everyone? And they provide tiny spreads, which clearly benefits individual investors. The NYT article says a FTT is necessary to protect from HFT, but they don't really have evidence of that. The study they link makes the case that a FTT would raise lots of revenue without distorting trading too badly, but admits that the effect on market volatility is unclear. But raising taxes so that the government makes more money is not going to be as good a slogan as raising them to punish some hyped-up evil doer.