That is partly the problem. You spend hundreds of millions to make blockbuster movies and then release it on Disney+ in a few months for free (or sometimes directly). That costs money. Add to that over reliance on only Disney content creates two problems:
1. You can’t have enough new content every month, subscribers therefore don’t keep the subscription year round.
2. You have to pay money to create content. Vs the ability to buy content for cheap or add it for a few months.
On top of that, Disney overseas also includes live sports in their packages which can get expensive.