The Principle of Contingent Causation: The Impossibility of Infinite Regress.

[Belacqua]

It's also a pure assertion that an infinite regress is impossible or even really a problem when discussing the universe. For all we know the universe is part of the regress.

It's not pure assertion. There are arguments against infinite regress. 

The arguments might be good or bad, but you'd have to know what they are in order to judge them.

Here is a brief outline:

https://plato.stanford.edu/entries/infinite-regress/