Longer answer: Qobuz, Tidal, and pretty much all streaming music services make use of Content Delivery Networks (CDNs). CDNs generally charge based on total data transferred, not for “pipe size” (which is what many people think of – you pay for 1Gbit/s and no matter how much of that I use, I pay the same amount). Because hi-resolution files are larger, that means more data transfer accrued, means more cost.
The real business answer is that it has little to do with cost. It has more to do with pricing to a target market to maximize margin. I think it’s a very safe bet that people who want high-res files are people who have a. more disposable income than rank-and-file consumers, and b. those people are willing to spend more to get high-res files. The marketing question for Qobuz then becomes what do we have to provide to capture that margin?
By way of analogy - a Mont Blanc pen really doesn’t cost that much more than an office supply pen in a box of a dozen, but is sold for thousands of times more. Is it worth it? It is to the people who buy Mont Blanc pens.
Quobuz has always said that they want 1 million subscribers with a high level of spending. They are very far from it and lowering the price in the United States is not a very good idea. Financial balance seems unlikely and investment capacity too weak for a very expensive business
The storage and bandwidth costs/track streamed are tiny compared to the (already tiny) reimbursement that Qobuz pays to the rights-holders for each track streamed.
I believe (though someone will correct me if I am wrong) that the latter depend on the resolution of the tracks streamed (i.e. the reimbursement rate is higher for “high res” tracks than for redbook.) But that may even vary from record label to record label.
I’m not sure, you would maybe need to ask Roon. Roon certainly doesn’t allow you to download stuff from Qobuz for offline playback like Qobuz does. Qobuz also lets you see what’s in its cache, whereas Roon doesn’t, so I suspect Roon doesn’t make use of a cache, though I maybe wrong. Pity if it doesn’t. I try and keep a good stash of music in my Qobuz offline bit so that if my internet goes flakey, or Qobuz or Roon go awol, I have plenty to play. And of course the offline cache it is really useful for phone and iPad playback when out and about.