Why does the world population tend to be concentrated on the continental margins

A majority of the worlds population tends to concentrate on coastal regions primarily for access to trade or business with other countries.

So  if  the sum of the enthalpies of the reactants is greater than the products, the  reaction  will be  exothermic.  if  the products side has a larger enthalpy, the  reaction  is  endothermic. you may wonder why  endothermic reactions, which soak up energy or enthalpy from the environment, even happen