and let's say, you got your winnings, do you think you will stop gambling? i don't think so. so you won't find your closure if you will not totally get out of gambling after such winnings. there's no closure as long as you are into gambling.
i don't know what others are thinking about the concept of finding closure in gambling.
The guy is just looking for excuses to continue his gambling. It is his statement to justify his action while others are seeing it as silly. Anyway, it is the guy's money so we don't have any say on his matter. Though we all know that chasing losses often ends up badly, let him experience it first hand, after all there are already lots of people reminding and telling him that he is doing it wrong.

It could be an excuse, using to justify his continuance on gambling in spite of the losses he has had to face. But I would also like to point out that there are several ways someone would find to quit gambling for good or for long periods of times: family, religion, time...
The important thing about all this conversation is that it is better to "find closure" by ourselves than letting the circumstances to start to decide what we do with our lives and what to do with our time/money. So it is better to know when to stop than letting our empty pockets to stop us when it is already too late.