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.
There are cultures that superstitious beliefs are part of their lives specially in gambling. And just like you said, the Chinese, it's been with them this beliefs ever since and so they are just one culture. And mostly it is also in Asian region that do have this, but there could be part in other world.
But then again, if you are really a gambler then nothing is wrong with believing in this thing. However, it's not the only one, still boils on luck if you play luck base games. And then strategy and knowledge in games like poker. And then you analyze the games when you are in sports betting.