I agree, and emotions is the most hardest test to overcome. When we win or lose our emotions are getting over to us. If we lose we try to recover it because we can't accept easily losing that money. If we win we think we can win more. Both situation just ends in the same result, the losing of money. Only few people can control themselves in gambling and it is hard to be like them.
I think this applies to those player that does not only bet the money they can afford to lose but also the money that is allocated to other stuff. Though I agree that emotions sometimes control us, but those who are not greedy, playing only for fun and know his limit is more likely not affected by either of those two. And you are right that there are only few who can control themselves.
We can become that person if we will continue to learn our way, it's a journey that along the way we will learn what must be done to control ourselves. In terms of information or method to learn how to control, it's open and accessible anytime in the internet, our focus now is to learn how to effectively implement it.