Black holes are just stars that have been crushed by gravity under their own weight and one key attribute of black holes is that they are smaller than their original size as a star.

Then was the super massive black hole at the centre of our galaxy a super massive star? If it was then it would stand to reason that there are other super massive stars, but where are they?

And I'm talking about stars the size of our galaxy, Because how else would you get a black hole as large as it is in the centre of the galaxy.