When we are doing something that we know is not incorrect or immoral but that we know other people may consider it to be the case then it is better to keep it a secret, as if you tell someone about the fact that you gamble and then that person tells to someone else you could easily end up facing some issues you never wanted to face with that person, however slowly but surely those outdated ideas against gambling are being left behind as gambling becomes more popular.
The right and wrong thing was based on the individual,some things are correct to some person.The same thing was wrong to other set of people,hacking was the illegal and unethical one.But to the hacker,the same was ethical one.Because they earn using the hacking,it was their own profession.The gambling itself not an ethical one to the Islamic community,other community people will try to use gambling as the real profession.So everything will be differ from person to person.If you are from the Muslim community,you can do the gambling with secret.Because the people from your community will do criticise your playing in the gambling.
Cultural differences is a big factor and yes, coming from your example regarding to hacker it was their profession and they find it profitable and there are also experienced gamblers who use gambling as a source of income, by following your statement, it's possible that there are times or there are people who want their gambling participation discreetly while other don't mind whatever behind them and will just move forward as long as there's no illegality with what they are doing, they've got that mindset that it's their money so it's their possession to control and to do whatever they like to do considering that gambling is part of their activities.
The issue of legality will be an important thing in gambling, when gambling is legal in your country then gambling has become a normal and common thing to do. However, when gambling becomes an illegal activity and is not permitted, then gambling becomes taboo and prohibited.
People who openly gamble are of course aware of what will happen, perhaps they will not question their gambling status. But there are some people who keep their gambling a secret. Now gambling is easy for anyone to access.