You can start one of those firms; in all likelihood, not all the potential profit has been extracted yet. You can hire a bunch of smart mathematicians and/or smart technologists, and spend time working on the problem. And then you'll be in good shape to beat the market. If you're an econ Ph.D. student hanging out on Hacker News, you're already well on your way to doing this with your life, if that's what you want to focus your life on!
But "you", the person with an unrelated day job fiddling with some investing app on your phone in your spare time, starting with a relatively small amount of capital compared to Renaissance's first year, and relatively small risk tolerance compared to Renaissance's first year, and definitely not enough money to hire a bunch of scientists full-time - "you" who's asking on a thread about passive income instead of lifelong career options - you are statistically unlikely to beat the market. That's what people mean by "You can't beat the market."