>>The social justice / millenial part of me hates this for being funded by high frequency trading, of all things. What a colossal waste of resources.

It's more efficient now than it used to be - by which I mean the total taken by HFTs is lower than what people used to pay in spreads and commisions. Price discovery is better (you get closer to a fair price if you trade) and spreads are lower. The whole industry that used to prey on spreads and ignorance of retail investors is gone. What not to like about HFT?