So how do you see this kind of lifestyle? Do you judge them as wrong because their reason is gambling, or do you respect it since everyone has their own way of finding happiness?
In as much as they aren't committing evil to fuel their gambling then it's fine, because I have seen lot of people who did all sorts of things to fuel their gambling desires. If people could work and still maintain a self gambling practice then it's fine and provided they are happy doing it and gambling responsibly there is nothing to worry about it.
Although, I don't think it's gamble that is causing them to work very hard, already they could be a hard worker who so much believe in working to make money than depending on people, so instead of staying idle after work they could decide to also try someone differently by gambling as well.
If you really most gamble, you need to work harder in other to secure your future and your gambling expenses, since you are not expected to use the money of your personal needs or other expenses to gamble, therefore working harder gives you the edge over any unforeseen gambling expenses that will rise later, if you want to be a successful gambler, actually, it doesn't really means that only gamblers should work hard, but for these set that feels they needs to work harder are called responsible gamblers because they know how important their gambling activities is and their personal expenses is and does not need to be mixed up together and they know that gambling is for entertainment unlike those that feels it an avenue to make money and start borrowing to gamble, those set of person of gamblers have a wrong orientation towards gambling.