But in this digital era, I doubt there are still superstitions like that believed by gamblers, it just that in the 5 things you mentioned I still believe in red as bringer of luck and of course this belief has become kind of culture for some regions and certain groups.
Color red is indeed symbol of courage and strength, even the Chinese consider it bringer of prosperity and luck and I in roulette game always choose red over black in betting on color selection for the table in numbers and it true that red brings victory more often.
Superstitions will still exist in every where and some gamblers still believe that things. But maybe we never meet those gamblers so we can say that no gamblers will believe superstitions. When we go to some places that still believe about superstitions, that will no surprise because that can related to their culture and their belief. Asian can be an example for that although that already reduced a lot where young generations will not believe something that is not seen. But if we talk about traditional gambling, maybe that thing still exist and be used by some gamblers because they are believe superstitions.