Judging from a gamblers point of view, I can vividly say that the only point whereby the risk involved in gambling can be said to no longer be worth it is simply "When a user through gambling start getting addicted to it", and simply  lacks self control & disciplined, which could be detrimental to his health as an individual. While secondly, the risk associated with gambling can also be said not be worth it is when the reward for winning a jackpot can never be quantified to the amount you may have lost during your years of gambling and loosing continuous bets.