If you've seen a system like this in action, it's a beautiful thing to behold and cannot be mere luck. Transactions stream in constantly. It's not just one big, lucky bet, but thousands of tiny bets with a slight edge. A plot of profit & loss with respect to time looks like an almost perfectly smooth upward line. And if you're good, you can do this every single day for years and years.

Still, I wouldn't say guys like that have beaten the market in a real way. I've certainly never felt like I did. This style of trading doesn't need outside capital and can't scale. If I gave you $100 and armed you with a scalping bot, I bet you could easily turn it into $200 buying hot tickets on Ticketmaster and reselling them. But would anyone call you a genius trader? Could you do it with a million? A billion?

As a business net of all costs like employee compensation and technology, returns to owners are pretty lousy. Compare owning Virtu stock to an index fund since their IPO. Ouch.