So it can be inferred that profit, in your world, confers benefits to both sides: you make money, the tenant has a place to live, but this isn't a fair transaction in real terms, is it, as only one side benefits in profit and the other loses in the transaction by paying whatever the landlord demands.
This is his privilege; or 'private law', to derive the original meaning of the word.
This is no bargain between equals: a landlord offers a place to live and the tenant pays rent to continue doing so. All the profit goes to him and the tenant makes nothing out of it. Profit, in these terms, is purely monetary, and to suggest otherwise is to ignore the basic tenets of commerce.