Decisions made by policy makers can have enormous impact on human welfare. Policy decisions involve setting priorities for where resources will be allocated. So, decisions about where money will be spent and not spent will affect who benefits and who doesn't. There are always competing demands for resources, and nobody will get all that they need. So if a government decides that it will spend money on war, then there will be less money available for schools, and kids will be affected. If a government, and by extension the people decide, that they will give priority to their older citizens, then there will be less money available for schools, or healthcare for others, etc.