Although it is the leading theory, the stellar collapse theory of black hole formation has some flaws. Firstly, at the center of most galaxies, there are supermassive black holes billions of times more massive than our sun. For these black holes to have started out as collapsed stars and grown to the size that they are, it would take longer than the Universe's age to accumulate that much mass. Secondly, based on the stellar collapse model black holes would exist in all masses corresponding to stars. However, only supermassive or relatively small black holes have been observed, no intermediate size ones. With supermassive black holes taking an impossibly long time to grow to size, and no detection of the logical intermediate-mass black holes, it is clear that there is much that is misunderstood about black hole formation.