Purchases of DRM movies are like purchasing an unlimited free rental card from Blockbuster. They are not yours.

Streaming services will even edit or censor movies as they please.

https://variety.com/2019/digital/news/hbo-edits-game-of-thro...!

https://scribe.citizen4.eu/everything-80s/why-are-streaming-...

Honestly the only way to preserve most digital-only video media today is piracy.