Irrespective  of your social status, either poor or rich, we still have our different roles to play and I don't know your standards for defining someone as poor but i think just as @Nwada001 has already said, that one of the major impact the poor can bring  to a society is the fact that they can actually provid cheaper about as co.lared to using machines for same jobs especially  if the job isn't a large scale one.

The poor also provide a whole lot of services the rich can't even provide and I even think the poor based on what many might classify as poor, are the people that even make life much more easier for the common man from agriculture to transportation down to even shelter building.
Generally,  I don't think the world can do without the poor