"Generally speaking, it's not all that expensive to port a game that already exists. The game itself may need to sell millions in total to turn a profit, but a port might only need to sell, say, 500k to recoup the costs of conversion."
No one enters business to break even.
This argument seems to be centered on the idea that turning a profit alone is enough to deem a project a success. It's not. The goal of a business is to leverage assets so that they deliver the most ROI possible. This is especially true in game development, where developers themselves are the most important resource. Developer time must be used wisely.
Resource management is the core of business. It's a lot more complicated than "if you can turn a profit then you should do it."
