What do you think could be the reasons that they are still gambling though?
This is not a generalizable answer but to answer the question one of the reasons why they still gamble is that it could be a habit they had when they were younger that didn't go away. Some habits you don't just pick up when you are an old person.
If you have been gambling in your fifties and you didn't quit, in your old age when you have all the time in the world, you can continue on those habits to keep life going.
When a practice becomes habitual, it continues unlike the age. Gambling is addictive as well as habitual. What we see with those aged people seems like it is habitual. They just spend limited money and find it a place to gather and have conversations. With the addicted ones, those are places where they try to profit. An addicted gambler can't continue gambling after his fifties because of funding. When it comes to habitual gambling, they know the limits and limit themselves, unlike the profit/loss happening with their activities, as the primary purpose of gambling is not to make money.