So in a free market, all entities inherently act in the best interest of their customers, regardless of whether or not there's competition? And they wouldn't us

So in a free market, all entities inherently act in the best interest of their customers, regardless of whether or not there's competition? And they wouldn't use their position to do anything anticompetitive to maintain that position and keep the "free" market effectively closed? My point is, without some entity establishing rules of fair play, the market isn't a free one, because one player can gain enough power to effectively close the market to any competitors.