You have to constantly create new content to bring in or keep subscribers; Many people have already seen Disney's old catalog of content. You cannot rely on the back catalog. This is true of every major streaming service providers (i.e. Netflix, HBO Max, Paramount+, Disney+, Apple TV+, Amazon, etc).
Production costs have gone up significantly these past few years. A decade ago, it typically cost $2 million to $5 million an episode (e.g.
House of Cards;
Orange is the New Black). You now have studios spending
$25 million per episode or more. Amazon spent
$465 million on season 1 (8 episodes) of
The Lord of the Rings: The Rings of Power; That's $58.125 million per episode!
Why do you think all of them are raising prices, cracking down on password sharing, offering ad-supported tiers, etc?