Answer: To protect the environment.
Step-by-step explanation:
One reason is to save the energy that is required to manufacture the new product from raw materials.
The second reason is to save the environment, the waste material that is produced ultimately is dumped into the environment it will cause waste generation. This can cause pollution which has both short term and long term health issues.
The new materials also requires money which can be saved when using the old material even if not the whole cost some of it can be saved.
There is a great need to save the environment from harmful and unnecessary generated waste which can be preserved by recycling the wastes.