G’day
The Universe does not need a reason to exist.
It exists without limitations.
It exists because matter cannot be created or distroyed.
It exists because matter recycles from one form to the next and this is where the fun starts in understanding the formation and evolution of form.
This is not coming out of my head, its coming from the many many papers explaining the events by using science and observations rather then ad hoc theories to make a model work.