Ofcourse to those people who are winning, they'd say yes, profit in gambling can sustain a daily living. But if it's for the majority, gambling will never be advised to be a reliable source of income simply because of the fact that winning is not certain. You won't always win the game. And for me, even if you have won a decent amount, it will still not validate gambling as a reliable soirce of profit. If you've been in this industry for years for sure you know that there are days wherein you'd lose continuously, sometimes for a whole week.
Someone who has just won gambling will, of course, as you said be able to buy all their daily needs, but in my opinion that is too much and even though it is true that the results of the win will only be temporary, meaning that the money if you win will not last long because you will most likely return the money to gamble with the confidence and hope that you will be able to win it back. Gambling is an activity where you will risk money or valuables that you have and there are only two choices that will occur between winning or losing. If one makes this activity a source of income to support living expenses, then what if you run into a loss when you need that win for necessity?
Having a huge capital would give you bigger chances to win but chance won't mean any certainty or guarantee of ending the day victoious. You could win, anyone of us can but if it is overall sustainability, it would still be a no.
No matter how much capital you spend, no matter how big your money is, it will still have no effect and cannot be used as a solution to win, because it cannot be used as a guarantee for a big chance of winning. Indeed, having large capital allows you to get big wins, but it does not rule out that there will also be big losses. I won't focus too much on finding ways to win, because for me gambling is just entertainment, if you're lucky, the win will definitely come by itself.