In a perfect system, I wouldn't pay a penny more than your total cost. Capitalist extraction can only occur because we pretend it's not an exploitation of unequal knowledge.
No, profit is just and economically rational compensation to the investor. Without it, the opportunity cost and risk of saving and investing, respectively, is not compensated for.
https://www.investopedia.com/terms/n/normal_profit.asp
"Economic profit is the profit an entity achieves after accounting for both explicit and implicit costs.
Economic Profit = Revenues - Explicit costs – Implicit costs
Normal profit occurs when economic profit is zero or alternatively when revenues equal explicit and implicit costs.
Total Revenue - Explicit Cost - Implicit Cost = 0
or
Total Revenue = Explicit + Implicit Costs"