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Gambling cannot be considered as an opportunity for regular earnings, as it is impossible to get a guaranteed profit. One-time winnings, regardless of their size, should be considered as an exception to the rules, in which the casino usually wins. So treat gambling as an entertainment and you won't be disappointed.
It is true and that is how it should be. I agree with you because that is the best way to approach gambling - not the opposite of making gambling a consistent source of income. If someone wants to get rich from gambling - then become an investor in it by building a casino in the industry. Gambling customers will only lose if they are really after winning - but if they are doing it for fun, then I don't think it is a problem.
Many problem gamblers are those who approach gambling to make money - and end up losing money. Many gamblers end up poor, jobless and so on - but those consequences are not felt fully by gamblers who gamble responsibly.