Yes, they make a few billion between them in an ultra-competitive, expensive to compete in environment. My wording wasn't the best, but what I meant is that HFT firms only compete with other HFT firms. They're basically all battling to offer the cheapest service possible to other market participants, and can offer even better prices to retail due to the non-toxicity of the flow.

Virtu has a market cap of what, 6bn? Citadel was valued at 22bn from the recent funding round. Those are the biggest players in the space, and it's becoming increasingly monopolised. Meanwhile JP Morgan has a market cap of 450bn, BlackRock a market cap of 110bn, and BlueCrest manages 40bn of its own money. Considering how much attention it gets, HFT is pretty innocuous. The notororiety is basically because they pay 23 year olds 400k/year and it sounds scary to outsiders.