The optimal amount of algorithmic trading is definitely more than none (I appreciate liquidity and price quality as much as the next guy), but arguably there's a case here that we've overshot a bit.
The price data I (we?) get is 15 minute delayed. I would guess most of the profiteering is from consumers not knowing the last transaction prices? I.e. an artificially created edge by the broker who then sells the API to clean their hands of the scam.
Real-time price data is indeed not free, but widely available even in retail brokerages. I've never seen a 15 minute delay in any US based trade, and I think I can even access level 2 data a limited number of times on most exchanges (not that it does me much good as a retail investor).
> I would guess most of the profiteering is from consumers not knowing the last transaction prices?
No, not at all. And I wouldn't even necessarily call it profiteering. Ironically, as a retail investor you even benefit from hedge funds and HFTs being a counterpart to your trades: You get on average better (and worst case as good) execution from PFOF.
Institutional investors (which include pension funds, insurances etc.) are a different story.
