Okay, a little Monday afternoon math and no calculators are required.
Consumers want the most value for their money. Value can be defined by the benefits provided by a product or service, divided by the cost of that product or service:
Value = Benefits / Cost
This over-simplified equation shows that for a given set of benefits, as the cost decreases, the value to the customer increases. It might seem that maximum value would be reached if the cost is zero. But if you remember your grade school math, you cannot divide by zero.