As you may know if you have read any of my blogs on Black Holes I have never believed them to be an entity in themselves. They are a products of the galaxy that they inhabit.Of late they have realised certainly super massive black holes have not had the time since the beginning of the universe to grow to their present size, never the less they try to imagine  a way to continue with Big Bang and some how imagine an answer will be found within current ideas and change nothing in their personal knowledge. Strangely it is often the case even in science that some of the cleverest people who have ever lived cling stubbornly to stupid ideas.  Ernst Mach never believed in atoms, The idea of tectonic plates was ridiculed for 20 years before being accepted finally. Aristotle did not believe that the heart was responsible for blood circulation and for 1,500 years his idea ruled until Harvey showed that it was indeed the beating heart. So New Gravity explains that as gravity is a pull on space and this movement of space moves anything else in its way accordingly. In the case of black holes at the centre of a galaxy a percentage of the gravity exerted by every star or other object criss crosses from all directions producing titanic forces roiling and accelerating any star in that area/volume.

Where super massive black holes are found they occupy massive galaxies and at the centre are a ring of very dense stars supplying extra power because of their closer proximity.
A galaxy of a trillion stars easily produces something the size or a billion suns. How on earth do you grow one otherwise?