Netflix pay a licence fee to the owners of TV series and movies for a set period. When that time is up, they either remove the TV show/movie or they pay a new fee and extend the licence.
That accounts for a huge part of Netflix costs.
If they make the show or movie then they can show it forever, and get other people to pay them for the right to show it in places that Netflix don’t have a presence.
If anywhere like that exists in a few years time?