Yes, some people are just like a parasite. Just like a mosquito that sucks blood from human, and deposits a plasmodium into the bloodstream, that causes malaria. They benefit, and harm. While many people are a parasite, we still have some that act as commensalism.
They benefit from you and leave you no harm. Some can still be classified under mutualism. They benefit from you and you also benefit from them. The greedy and callous ones are really a parasite that should be fed to the fowl.