You need the initial prototype to test your idea, and then you need a few more prototypes to test your product and see how it can be improved.

It is less expensive to make the product because 3D printing doesn't require any molds or machining.

When you first start using and/or selling products, 3D printing can fulfill your product needs up until the Product is well-established. Even then, for many applications, 3D printing means that updating the design only requires updating the design file, and every product made from the time of the update is the latest and best.

Therefore, 3D printing is not recommended unless your product sells in huge quantities with little revisions (in which case we will introduce you to manufacturers).