~snip~
Those gamblers that complain of having stress because of gambling, they are the ones that caused the stress upon themselves because like you have explained in your comments, if a gambling didn't handle gambling in such way that they did, they will never be stressed out. When a gambler control their habits, they will not be addicted.
Yes, I think this is really the main point.
When gamblers start to gamble with money they don't have, then that's when the problem start to appear.
The odds are against the gambler, so basically it is a matter of time until they actually lose that money, and they will start to panic.
That's when the stress levels start to rise, and there's not much they can do other than stop gambling really.