It’s cheaper to pay for the 2TB iCloud for 2 years than it would be to upgrade to larger storage on the phone. It’s actually even less because my whole family uses the same quota together.
Then it's easy decision to throw in a few more dollars for streaming service and you are nice recurring revenue instead one-time sell.
Also it's probably cheaper only if you consider only Apple ecosystem. Other mid-range device comparable to base iPhone with bigger storage is probably cheaper.
I want to upload it all to the cloud as fast as possible so it won't get lost if the device is stolen/breaks/gets lost.
The idea that all of my media would be stuck on one device and at risk or that I would have to go through the laborious process of manually syncing it all regularly by hooking up my devices is a nightmare.
Everything automatically syncs to all my devices, including photos and videos me and my SO take in each other’s presence, all recent media is immediately available at the highest native resolutions and I never have to worry about anything.
I’ve got terabytes full of stuff going back years and for good measure I’ve got an automated backup running to a NAS.
Out of an old fashioned mindset I’ve got a moderately upgraded iPhone with 256GB, but 200GB of it is apps because I tend to download apps from fellow developers.
A fraction of that is spend on photos and videos because of automatic storage optimization and a fraction is used for music and podcasts that’s also automatically managed for when I’m traveling.
I’ve got professional cameras and by far the most annoying part is transferring media despite having access to the highest theoretical transfer speeds available on the market today.
Like, there is a value in what Apple is offering. It means someone like my mum never ever has to think about storage or backing up anything, when she lost her phone she got a new one out of a box, signed in and all of her stuff was there without having to do anything. As a power user, could you achieve the same for less? Sure, but for average user the value is there.
Modern customers stray further from God every day.