To me you have to define what wearing out is.
If you mean the ball becomes unusable because the ball return will not pick it up, large holes and gouges in the ball, falls apart, or some other physical malady, then I would say very few balls become completely unusable.
If you mean from a perspective that the ball has lost it's effectiveness to carry strikes, react to oil and dry, etc. Then yes balls will wear out over time.
Nothing rolls like a new ball, not even resurfaced ones, but older balls can be used effectively.