Our duty should be to make this world a better place than when we found it.
Well each of should have a duty. The duty to make this planet a better place than when we arrived and to future generations who will still be here when we are gone. But as people earn money they can decide what they want to do with it, and IF they want to contribute positively or not. That is something we cannot force others to do.
It's our own decision, and we decide what are our responsibilities in this world. But most people are too obsessed with their own well being and pursuit of wealth and sometimes to the detriment of others. Some do it by being dishonest and taking advantage of others, because they feel entitled.
Others do it in an honest way and believe they should contribute to others. They realize and feel the benefits of making a difference in the lives of others. They feel amazing in making this world a better place. That is something not everybody can experience and feel. The emotions of giving and being grateful to our existence and the well being of others.