The most universally relevant subject to study would be the probability branch of mathematics and in this its highly applicable for the pure numbers side to a game even minus a person you can 'autopilot' out the trajectory of most games.    Sociology or psychology I think would be more relevant there as to what motivates people in terms of playing vs knowing it is a business with a cost to it.  You could theorize the flight fight response and how this raises adrenaline levels and could be linked to gambling.   Like alot of high energy sports there is a large amount of risk and competetive element in there that we as humans are motivated to take part in from our heritage as hunter gatherers.  
  Economics I find only relevant via gambling as an instrument of taxation in an economy.  Law because gambling is often restricted is relevant from that sideline.