In gambling it is not those with high intelligence that have long term earnings. It is those who are persistent. Even a fool who is persistent will be more profitable over the long term if they are able to stick with the recommended gambling strategies.
It is persistence not intelligences. I can even say that highly intelligent people may likely not gamble because there is no intelligence required for it and gambling is not in anyway mentally stimulating. Rather it is only dopamine stimulating and highly intelligent people are looking for brainy stuff.
A sign of high intelligence is also knowing when to stop regardless of your winning or losing situation at that point in time while gambling.
I am not at all sure that the persistent fool will be profitable in the long run. Persistence is a quality that can bring success in other areas, for example, in business. In real business, there are often situations where you are required to persist and persist in achieving your goals. The most important thing, the main thing that persistent fools can survive in the long run is the low cost of mistakes. In business, mistakes can really be cheap, although this is not always the case. In gambling, mistakes are almost always expensive if you measure them as a percentage of the entire deposit. The high cost of mistakes will not allow the persistent fool to have significant profits in the long run.
I think you missed the part where he said, that the fool gamblers are being recommended by a gambling strategy, (a well-working one). Now that makes them to be profitable. If not, they still can transform their selves because they are persistent. So intelligence really/also can play a major role. Usually, a naïve can make a lot of costs, especially in the gambling field. In doing real business, normally we always have a decent budget here because they are more complex.
So we can say that mistakes here can also be costly. It may seem tragic but they can be a good thing too, although if we are able to minimize or avoid it right from the start, then why not? That seems even better.