It’s quite sad as your friend has created a theory that keeps him motivated enough to continue gambling even if he continuously looses. I doubt he hardly thinks of his losses as he probably has his eyes set on the big win. The big win that’s just around the corner.
An average gambler cannot afford to play daily with unrealistic hopes of winning it soon. He could lose literally everything and if he takes such an advice. Addiction would not far off as well. Your friend needs help and definitely need to take some time off gambling.
Without a doubt the friend of the OP has huge issues, but what it is more aggravating is that once a person is so convinced about anything, persuading them they are wrong is almost impossible, the OP will need to wait until their friend has lost everything so they can finally open their eyes and see how mistaken they were, but even then this may not cause them to stop gambling, and this is because they will realize how difficult it may be to put their life back in order and they may prefer to not even try.