You are merely asserting this to be true.
That not everything has a cause can be demonstrated through reason.
If everything had a cause or condition for its existence outside of itself, then that would mean every reality must receive its existence from something outside of itself. The cat receives existence from its formal principles, DNA, the Oxygen it breathes, the food it comes, the molecules and atoms that make it up; in time, too, the cat is dependent on a number of factors – its parents, the evolution of mammals, and so forth. But all these conditions are also caused. The series doesn’t stop there.
But can all causes themselves require other causes? If that were so, the cat could never exist, because the fulfillment of conditions needed for that cat to exist in the here and now would be unattainable. If there is no ultimate reality or condition that is itself not conditioned, then that means everything is merely receiving existence. But nothing could receive existence if there were not some reality that had existence in itself.
If everything has a cause, then nothing is explained. Nothing could exist.