The production of physical copies of games is indeed expensive for publishers. Journalist Stephen Totilo from Game File found out from sources in the supply chain how much it costs to release discs.
Mass production of a dual-layer Blu-ray costs about $10–11 per disc. At a game price of $70, this is approximately 15% of the cost. Shipping, storage, and intermediary markups add to the expenses. Large retailers like Media Markt, according to Totilo, take another 15–20%.
The process itself is also not easy. The publisher informs Sony or Microsoft of their desire to release a physical version, enters into an agreement, after which the console manufacturer certifies the game. Then the cover is created, and the publisher and factory determine the disc capacity. Single-layer 25 GB media are cheaper, so some data sometimes has to be downloaded from the network.
As a result, even the 30% commission of Steam or PlayStation Store can be more profitable for the publisher. Digital platforms take a percentage of the game's price, while the production and delivery of discs have a fixed cost, regardless of whether it's a AAA hit or an inexpensive indie project.