There must be a striking balance in the world that no matter how each person in the world works twice as hard still not everyone will become rich. If we all become rich there are certain services we would lack people to render because no rich man would want to do those manner of jobs.
Most wealthy people in the world are not wealthy because of hardwork that those that are poor couldn't do, they got wealthy because they were privy to informations and connection that others weren't fortunate to.
hard works doesn't guarantee that you will become rich because if hardworkers become rich then Labour will be the richest person all over the world. Sometimes lazy people get the reward because of knowledge and hard workers remains in the same state.
According to my opinion poor are more hard working than wealthy people. Other thing is that some people become successful because they have strong support from their parents and strong foundation of wealth from their ancestor which make them more wealthy.