According to big bang theory the universe was one big black hole at the start

"This research was mainly driven by the desire to understand some of the most challenging astronomical objects -- supermassive black holes in the early Universe. These are extreme systems and to date we have had no good explanation for their existence," said Marco Mignoli, an astronomer at the National Institute for Astrophysics (INAF) in Bologna, Italy, and lead author of the new research published today in Astronomy & Astrophysics.

If we believe in big bang, then we believe in lots of black holes.