I think it is important to distinguish between spending too much time and being an addict. Lot's of people spend too much time. It doesn't mean they can't control it. It just means they prioritize it. You can always give them the quiz to see if they are an addict. If they start lying about the answers or refuse, better tread carefully and seek advice on how to help them. Someone who just plays too much will likely rationalize with you and may even be up for a better suggestion or make time to do something else if it interests them.