I had a friend that gambles only during the weekends, he claimed to gamble for fun only but In two weeks he was losing more than 300 dollars, and I asked him if he an addicted gambler but he denied it. Most gamblers are just afraid to admit that they are actually addicted, it doesn't matter if you gamble occasionally as long as you have no limit or control those few times you gamble you are dealing with an addiction problem. How do you know someone is addicted to gambling? It's very simple, if they keep losing significantly and it keeps progressing, that's an addiction.
For him to lose such a huge amount of money just within a couple of weeks shows that he's addicted into gambling, of course is very obvious that he's addicted into gambling. Moreover, I wasn't surprised when you said that you asked him if he's addicted into gambling and he possibly denied it. of course is only few person's that can accept the fact that they're addicted into gambling, probably when you saw them possessing the character of an addicted person.