Indeed, most arguments against HFT say it's a parasite business. However, I haven't seen anyone give precise numbers on how much money they're "stealing" compar

Indeed, most arguments against HFT say it's a parasite business. However, I haven't seen anyone give precise numbers on how much money they're "stealing" compared to how much money non-HFT hedge funds and investment banks make. I suppose this is the internet where everyone is an expert.