Technically you dont own your physical library either. Not entirely. When you buy any media (movie game music) you're buying the license to use that media. But because of End User License agreements the publisher retains rights over the product and can dictate how that product is used. This is the case for physical and digital media and has been for a long time. That's why they can tell you you can't have theatrical viewing parties of their movies with your own physical copy of their movie. For example, if you had a viewing party of 20+ people at your house and advertised it a studio could shut that **** down if they wanted to. Fox has done this with viewing parties of 35 mm screenings of A New Hope. They can do it with bluray screenings. Or any other format.
It's easier for them to exercise their right to the product with digital media but there are ways to do it with physical media as well. For example, bluray players require updates to function properly with certain discs. It was a real problem in the early days of bluray. People would buy discs and they'd be entirely unplayable in certain bluray players. Some discs wouldnt work at all until the player was updated with a firmware patch. The studios and bluray player manufacturers didnt always get those patches out in a timely manner. Nor did they have to. They could let some owners of a movie wait forever not being able to play the discs on certain bluray players. Also recently a game publisher, bethesda, sued a person for selling their unopened copy of a game because the person sold it as a "new" product. Bethesda said there was no way for them to know the game is in fact new and since this individual wasnt a licensed retailer Bethesda wouldnt allow him to sell it as new.
Bethesda blocks resale of a secondhand game (update)
So whether you buy digital or physical there are always risks that a studio or manufacturer could screw you and your media library over in some way.
I buy some digital for the convenience and to save space in my home. My library of physical bluray and UHD is approaching 1000. Movies that I dont watch but once in a blue moon I'll buy on digitalHD. Buy a lot of tv shows on digitalHD as well. But other films like Star Wars and the MCU I buy in physical copy.