Let's say I have a startup. I want to give my customers the most value for their money so I take the most economical path to creating my product... in doing so,

Let's say I have a startup. I want to give my customers the most value for their money so I take the most economical path to creating my product... in doing so, I reuse software written by someone else and released by them with a license that allows me to use it without paying anyone... which is one of the major reasons I decide to choose it. I didn't ask this guy to create the software and I am not asking him to maintain it either. If he abandons it, I will have to reevaluate by business but that is the risk I am willing to take. So how and where did I exploit anyone? Had I chosen to hire a developer to re-write the same functionality provided by that software and pushed the cost to customers, would that be better? For whom? How? Would it be any different if we were a huge company? Why?