Labour for me is human productive effort towards achieving set target.To answer the question, labour may be wealth, in the sense that when others labour while you fold your harms and watch from where will the wealth come from? Wealth creation cannot be separated from human effort both mental and physical.
You know one could also labour so hard yet nothing to show for it. it's not just about working hard or labour it has to do with several things hence success or wealth can be created.
In my place their are set of people know for all the hard work, they can work so hard do everything but they still remain the lowest in wealth creation, in as much wealth is concern you must put lots of things in consideration to create the wealth you desire.
Maybe luck is a little involved there so that there are some people who have worked hard but did not get the results as expected, but I think when you have tried to step then at least you will get an experience that will be a lesson when for example your hard work does not achieve success. Like a group of people in your area that you have mentioned who have worked hard but are still in a low situation in life, but I think I will not conclude everything too early, remember that there is no measure of the length of time a person must go through, and that means that maybe the group of people you mentioned are those who are still in the process of achieving something big and proud, because after all hard work is one of the keys to success.