That doesn't mean that gaming makes you like gambling. There are many player archetypes, some of which get enjoyment out of games from factors that are quite dissimilar from gambling, and they will probably never gravitate towards it. I could see the reverse being true though, probably gambling does make you like some kinds of gaming.
Also, this is saying that online gaming is correlated with online gambling. Well yeah, it's all sitting at the computer playing competitive games against strangers, money or not it's a similar activity.
Indeed, they show no correlation between "playing games at 9" and "online gambling at 20". It might be the age difference, but it also might be that gaming in general has little correlation with online gambling, it's just competitive online gaming that correlates, which makes a lot of sense.