Hedonism is the belief that Happiness is life's most important goal, whether for others or for yourself. You are a Hedonist if you think our life purpose is to make others happy.Morality is based on other people's happiness (not self happiness). If we based morality on other people's happiness, it would be trying to make them happy and helping them. If morality is based on self happiness, then yes, I do agree it is hedonism because all that person will do everything for their own gain which is very wrong. but morality can only get to the person if the brain developed well enough. I remember reading a news article where the all the murderers didn't develop a part of their brain well enough so they think killing is right and don't feel guilty when they do bad things. .
Like I said before, I could make a whole lot of OTHERS happy by lieing to them, but I tell them the Truth because I believe that morality is objectively given by God.