By migrating from Apple's 30% fee to a payment processor that charges only 3%, your revenue would increase by 38.6%. The only way that additional revenue would not make up for your development cost is if your revenue were low in the first place. There are plenty of developers who would gladly integrate another payment API for the additional revenue.
My revenue wouldn't necessarily increase(unless maybe price reduction drives the sales enough), my costs due to Apple's commission will decrees and my development and legal costs will increase.
My landlord doesn't care. From his perspective, all that matters is that if I make enough money to pay the rent. He is not interested if my revenue after Apple's cut has increased.
If my net income decreases(because my costs increase more that the revenue after Apple's cut increase), I am screwed.
