It rarely is just £500 - there are the lottery numbers, the scratch cards, fruit machines etc. The problem is not how it starts but how it ends.
My father was a hard working man all his life and very frugal with money. He did like an occaisonal flutter. Whenever he was on holiday he would want to gamble a bit and set aside a few hundred (probably going over as well). It was never a problem and they retired very well with healthy savings.
When they sold their big house they made a lot of money and moved to where there are a lot of casinos (and better weather). Because he was retired they would visit the casino for entertainment and the food once a month. Gradually the frequency increased. To make a long story short their savings are gone. The money to buy a smaller house is gone as well. As he lost money he started betting bigger to try to recoup it. The more bad luck he got the more he believed his luck would change and would strike it big. The only thing he likes doing is gambling. They love the glitz of the casinos and he has a social life around going to races.
It makes me feel ill to lose £20 and I can afford it more than they can. I would rather go shopping or put it towards a holiday - at least I know I am getting something.
I worry now for my mother. They have a good pension and are living off that. However with no safety net and no savings whatsoever I worry about what will happen. My mother says she is now paying closer attention to the finances as she never did before and trusted him. I wonder if she really knows how bad things are. They are in their mid-late 70s and his health is deteriorating.
He managed to keep it in check for 65+ years until retirement boredom and the bug really bit. He knows he has a problem and is trying to manage it.
I do not believe it can be managed. He needs professional counselling to find out why he does it and get tips to reprogram his thinking and get control of the urges. He has to do it on his own. You bugging him will only make him get better at concealment. That is when things really go down hill fast because the brakes are off then.
The more his secret is out in the open and he is able to discuss it and tell you about the more likely he is to control it. This is because shame and not wanting to appear weak will be powerful weapons against the addiction.
Good luck, you will need it.