Comment on the Origin of the Supermassive Black Hole
  We give the comment why the supermassive black hole exists at the center of almost all galaxies. We consider the origin of the supermassive black hole from the point of view of the density of the matter. If the density of the matter is fixed and such matter can come together by the gravitational attraction, such stellar object eventually becomes the black hole. If the density of the matter is that of the atom, such matter naturally comes together to form the black hole by the gravitational attraction. This is expected to be the process to form the supermassive black hole. In this way, we can understand that there exists supermassive black hole at the center of almost all galaxies, because there is no delicate process to evolve into the black hole. 
Kazuyasu Shigemoto