Aha, it’s an ontological question. Most mathematicians believe that numbers, sets, etc don’t exist in the world we live in, but exist in a special world called “Platonic world”. That’s what Platonism in philosophy of mathematics is about.
In other words, it is an issue between access and existence. Does access need existence? For instance, when X says 'John is charismatic', is 'charisma' like 'neurosis'? Definitely not, and X sees John's charisma. And this charisma doesn't play the causal role.