Saying there is no cost to streaming scaling is not entirely true. The service still pays for the data transfer and running servers per user; and the cost is highest for ATVP where all content is in high bitrate 4k HDR. They are still paying royalties to the creators. And it needs constant updates with new content which is not that easy to aquire.

And while Apple currently outsources production, it's not as trivial as you make it seem. Making a modern TV show is a business for thousands of people. There is big logistic behind each, and Apple orders dozens of them every year.

There are services with low upkeep, but this one has to constantly evolve with new content making it quite costly. Apple supposedly spend 22 bln dollars on R&D in 2021 - compare it to 18 bln dollars that Netflix spend on content creation and something like 7-8bln Appletv plus had budgeted.