Preventing HFT would mean exchanges make less money, meaning they'd either have to charge more or find a new way to subsidize market activity. It's akin to how

Preventing HFT would mean exchanges make less money, meaning they'd either have to charge more or find a new way to subsidize market activity. It's akin to how Robinhood sells data to trading firms to subsidize trades for long-term retail investors. "Economically productive" isn't always black and white.