How can a galaxy not be disk shaped

Question

If a galaxy is the accretion disk for a supermassive black hole, how can it be a shape other than disk?

Answer 1

Because it is not an accretion disk. Accretion disks occur when matter orbits a massive object in such a way that it interacts with itself, losing energy through frictional heating and converging into a hot disk. A galaxy consists of stars orbiting their mutual center of mass, without any appreciable friction or other violent interactions. There may certainly be a black hole at the center, but it is much smaller. A galaxy can be elliptic or irregular, depending on the orbits.

Answer 2

In a galaxies early stage it’s not disc shaped and doesn’t necessarily have a black hole. When two galaxies collide they can disturb each other so much they become sphere shaped and start forming a disc all over again.