The employer is adding $5/hr of value to the end product. That is their profit.
You cannot pay someone $5/hr to provide them with $10/hr of value. You provided them with $5/hr.
You can pay someone $5/hr to provide you with $10/hr of value. In which case, you are undervaluing their work by $5/hr.
What is "$10/hr of value" as distinct for what you paid for it? Is it based on how much you sold the end-product for?
If that's the case, you paid $X/hr to earn an extra $X/hr - in other words no extra profit, is that not correct?
The employer is adding $5/hr of value to the end product. That is their profit.
You cannot pay someone $5/hr to provide them with $10/hr of value. You provided them with $5/hr.
You can pay someone $5/hr to provide you with $10/hr of value. In which case, you are undervaluing their work by $5/hr.