If you continue the thought process that led to this question in the first place – which is not a bad question, by the way – then you would also ask the same questions about art, music, theater, fiction writing in general, movies, and any other form of non-edible non-structural (shelter-related) or other capital / infrastructure production. Why do those exist at all? How can we “afford” them?
We can afford to have those elements in our lives – assuming you don’t live in North Korea where it is compulsory to support those things but not enjoy them – because we produce enough of the essentials, and can trade with others making other goods, to build up additional wealth in societies all around the world. That is, the economy that does exist to pave roads (and why do we need roads, by the way?) and grow and distribute food and mine and refine metals and fuels, etc., is so productive that it allows us to accumulate wealth to spend on non-essentials such as entertainment.
Don’t forget the popcorn.