There are lots of shades of random. When the three-photon photoelectric effect will happen is random, but if you can find a way to bet against it, unless the odds are ridiculously skewed, you should.
But the odds are ridiculously skewed - that's how it works. They're skewed so the house always wins, which means the customers, taken together, always lose. If everyone's betting against the three-photon photoelectric effect, you will be able to multiply your money by precisely 1.0 when your bet comes true and it doesn't happen, or maybe even 0.999.
The house here is just taking some money off the top. It doesn't really matter whether the customers, taken together, get 100% or 98% of their money back. What matters is that an individual that's a few percent more accurate than the market can make money.