You can't possibly argue that doing billions of trades a minute has anything to do with real-life liquidity. By real-life, I mean liquidity that's relevant to a

You can't possibly argue that doing billions of trades a minute has anything to do with real-life liquidity. By real-life, I mean liquidity that's relevant to a bank's customer, eg. a private citizen who possibly even owns a trading account. And that's the only kind of liquidity I care about. It's just a game to extract money from the economy without doing real work.