Drinking can be bad if you get drunk. Eating can be bad if you become a glutton. Taking naps can be bad if you become a lazy sloth. Going to the magazine store can be bad if you find yourself buying bad magazines.
Gambling can be bad if you overindulge and abuse it. But it is not bad in its own right. I love just sittingdown with my family and playing some poker. Granted, the stakes are always pennies, but that is still technically gambling, and I can’t believe anyone would consider it a sin.
Also, lots of Catholics gamble, but then again, lots of Catholics get drunk, adulterate, and do a lot of other bad stuff. And amazingly, lots of non-Catholics do too!!! lol, no one is perfect, and if it seems like more Catholics are doing these things, it is only because there are more Catholics.
Although, there are also quite a few un-devout Catholics who, while claiming to be Catholic, blatantly and knowlingy break the Church’s rules anyway. You can’t blame the Church for what her members do. (No saying you are, just saying)