Why Is Everything That Exists an Explanation?

Proponents defend the first premise by inductive reasoning. They say, look, every existing thing we know of has a cause. So how do we respond to this? Ts, there's so many ways. Here's one, just point out that this is a black swan fallacy. For millennia, it was universally accepted that all swans are white. In fact, this truth was so incontrovertible that logicians would often use it to illustrate the process of deductive reasoning. Yes, all existing things seem to have a cause, but maybe in certain conditions there's a black swAN. But fair enough, the intuition is still pretty strong. What about this? We