You can't buy or sell stocks without trading with someone else. HFTs give you a lower price when you do that (otherwise people wouldn't trade with them). To the extent that they're redistributing wealth, they're redistributing what would have previously gone to a traditional market-maker, partly to themselves and partly to the person making the order.
I mean, if a supermarket sells strawberries for cheaper than your local greengrocer, is that "a non-negligible amount of money for a service with questionable value"? It seems to me that the onus there isn't on the supermarket to show that strawberries are worth the price.
I mean, if a supermarket sells strawberries for cheaper than your local greengrocer, is that "a non-negligible amount of money for a service with questionable value"? It seems to me that the onus there isn't on the supermarket to show that strawberries are worth the price.