You may value world peace but unless your sole concern is trying hard to make it a reality then it isn't a high priority. Those who act and do their best at making world peace a reality are rewarded by contributing to the cause and not the success. They value peace and although you may not get it they are satisfied by at least trying to make it happen. The confusing part is that if you value making others happy over your own happiness then it is okay sacrifice your own happiness to bring happiness to others. Acting on self-interest does not necessarily mean acting on one's happiness. If you truly believe that contributing to world peace is what is the best thing to dedicate your life to, then you are acting on your self-interest. Like the old saying, "It's the thought that counts." They may have not brought world peace but bringing, new gun laws, ending slavery, working on medicine, anti-drug protesting or whatever you may see as a selfless act is good enough. Acting on self-interest does not have to mean being happy or being successful. If world peace or any other seemingly selfless act is valued and personal to you then you are acting for your own personal advantage.