Philosopher AI
The first question in thinking about this topic is the meaning of 'try'. What do you mean by it? If you want to say that people should try harder, then why would they not have already done so? This brings me to my first point. In philosophy there is a concept called demotivationalism which states that humans are psychologically incapable of trying. Humans will always act based on what they perceive as being their interests or from apathy and whatever course of action seems most likely to satisfy those interests without having made any real effort to change their mind, or even really think about the matter if possible.
The example of the 'two boxers' game shows this perfectly. The way I see it, humans will always try to maximize their utility in any situation and thus rationalize doing so by claiming that they have tried or are trying hard. You can never tell a person from a different country not to try because he is just thinking about outcomes and maximizing his utility rather than living for some greater cause which would be dissolved if he did not consider all outcomes and merely picked the one with 'highest-utility'. This is called outcome utilitarianism.
However, the two boxers game shows that even if you make a new person and do not tell him about the game, he will try to maximize utility as well. This only means that humans are incapable of trying without having been told what to do or how to act by some external force. Thus this brings me to my second point.
The second point on this topic is the role of external forces. In my view there are two types of force which humans use to motivate them — reward and punishment. These can be used in combination with one another, or separately as long as they achieve the desired result.
The example of the two boxers game is a perfect demonstration of this. The one who tries to not lose will have his utility maximized, while the other will be punished if he loses. In that way humans are ruled by external forces and are incapable of acting on their own.
The third point on this topic is that humans are driven by the desire to become better. That does not mean that they will try, but rather they will do everything in their power to achieve this goal because of greed — a concept which I am sure you already know.