I think you or we cannot rule out the fact that actually happens in gambling where most people or gamblers make gambling a place to earn, or simply they always prioritize winning in every bet, I understand that whoever it is that even though they come just for entertainment but still they will never refuse the name of victory but maybe the difference is that there are some gamblers who are too pushy to win and there are also those who wait with patience and maybe you also already know the two types of gamblers that I mentioned.
The gambler who want to earn money from the gambling site,need to increase their skill in the gambling site.The winning money in the gambling site can be increased based on their ability to make money from the same gambling site.The gambler with huge money mostly consider the gambling as the entertainment,because they doesn’t need any money to make them rich.Because they are rich already,this was the reason the rich gamblers easily increased their skill in the gambling site using their money to gambling site.The gamblers who want to multiple the money mostly take the big risk will leads to the big loss.
If they are involved in sports betting then yes maybe I would agree with your idea that they need to improve their skills and knowledge about the world of sports because indeed this is also quite helpful for you to get closer to the possibility of winning but what we should not ignore is that no matter how and where you gamble there is still the possibility of losing, or that means you can never avoid the possibility of losing even if you are very skilled. Yes, it is quite reasonable that it is very unlikely for gamblers who have a rich background to have a mindset of earning in gambling, as you said that they are already in a good financial situation and already have their own way of making money for sure so this is enough to be used as an excuse that most likely the rich make gambling just for leisure time to get entertainment, and this means that the financial situation is enough to influence a person's mindset in terms of addressing gambling, simply put, people who have below average finances are more likely to make gambling a place to earn which is actually a very wrong idea.