It's said about brain that, "use it or lose it" — now, question being, do you think if person plays brainless gambling games such as slots, dice for major part of his/her daily routine, will it make him/her dull?
Edit: "brainless" as in playing gambling games that does not require using brain, I thought it was clear especially given examples.
Perhaps it’s true that we might use a less power of the brain when playing some games in a casino especially those you mentioned as they require less or almost nothing to do with thinking as basically they depend on luck. However, it’s impossible not to use the brain in any instance, basically in biology; the human brain works all day even during sleep hours, only the body retires but the brain and mind stays at work hence it’s not possible not to use brain in any game as they still require you to choose between this or that in taking your chances.