It’s very hard to pin point anyone with an online gambling addiction because you don’t see them playing physically and most of them doesn’t share their experiences even with partners and closest friends if they are losing huge amount since this is shameful.
And it’s very hard to to give an advice for an online gambling addict to stop because online gambling is very accessible. Yeah sure, it’s easy to tell them to self control or whatever advice but it’s very hard to implement in actual because gambling games is so addictive. They will not fall on addiction state if self control is easy to achieve. I will leave this part to professionals on how to solve this kind of issue.
But reminding those people can somehow help them to limit their bad gambling habits. If there are people who are constantly checking up on you, some might feel motivated to do better. It's not really a hopeless case even if someone is addicted on online gambling, as long as they are willing and determined to change, nothing is impossible.
The only time it will become impossible to overcome is when they've disregard the concerns given to them and become impulsive and irrational anyways. People can be greedy and this sadly causes most of their downfalls. Being too independent too because of having the "i can do it all alone" idea in their minds. It's not bad to be helped, be guided, and supported after all. Gambling addiction can be solved by right intervention, willingness, and having the strong support system.