Hobbies are indeed pleasures that someone wants to do in order to fulfill their desire for pleasure and be able to fill their free time with things they enjoy and it is up to them to use their hobbies for whatever they want, but most people describe hobbies as doing things that are useful for themselves, such as swimming. it can make a person taller and it is a good hobby, there are also those who play games but make it a daily hobby because they don't have a job, there are also those who like fishing because they are bored at home and want to do activities with their friends. There are lots of them a hobby that's actually not very useful but is very fun so if they take up gambling as a hobby, I don't think it's a problem because gambling is also part of the game.
But what you need to remember is that gambling is a negative hobby if judged by other people because it can cause danger to people who use it, therefore if someone is thinking about eliminating boredom or filling their free time with gambling, use gambling wisely and always be careful in managing their finances so that did not experience major losses.
Indeed, a hobby is something that is done based on one's own desires because it can make us happy to do it, as you said, swimming, fishing, playing games have benefits. But of course everything we do has its own risks, now if we like playing games and don't have a job it can make things difficult for us. because playing games too often, in my opinion, is not good, there will be a feeling of being lazy to move other than playing games. It's the same as gambling, which has a bad impact if you make it a hobby, unless you can control yourself as well as possible, it's not a problem, it's just that many people gamble excessively, which is not recommended.
I myself like gambling, but I don't make gambling a hobby, because I have bad thoughts about gambling if it becomes a hobby. As you said, making gambling a hobby can be dangerous, so if you really like gambling, it's better to gamble sensibly. In my opinion, it's not advisable to make gambling a hobby.