The cosmological argument

Hello Rabbi. One of the assumptions of the cosmological argument is that the existence of the universe is not necessary, that is, that the universe is a possible reality and a type of contingent object in our experience (and therefore the second assumption applies to it, that everything that is a possible reality has a cause) – and one of the explanations you gave for this in the notebook on the cosmological view is the scientific theory of the Big Bang, which says that the universe was created at a certain time. But according to the theory (correct me if I’m wrong) the universe expanded from a state of a single singular point that may have always existed. And if so, what makes the universe not obliged by reality?
thanks.