What market is Disney a monopoly in?
https://nyunews.com/opinion/2019/10/01/disney-public-domain-...
Amazon only managed 35% of ecommerce. There are a lot of other companies trying to eat their market (Ebay, Shopify, Ali). Hence prices there stay low.
Technically, the barrier to kids’ media is low too, and there’s tons of it, for free even, but it’s mostly garbage. What Disney has is a curated, higher quality (according to the market) product.