I look at this as being similar to (but not the same as) buying fast food. You will always save money by buying ingredients and cooking food yourself, but with fast food, you're paying for the food PLUS the convenience of not having to cook it yourself and getting it much quicker than you would if you did.
With software, under a subscription model, you get the software, and less worry about updates, upgrades and the chunk of cash you have to lay out for major version releases. Plus you may get additional content you'd otherwise have to pay directly for. With Presonus Sphere, you get Studio One, Notion, cloud storage space and a significant amount of additional content plus exclusive tutorial videos for an expected price that's easily budgeted for most people.
In my case, I'll pay a little under $400 over 2 years; this is less than I'd otherwise pay for Studio One and Notion, assuming I wanted both. Of course, with upgrade pricing, it would be cheaper to buy both directly. But, considering the additional content and storage I get with the subscription, it's well worth it FOR ME. It depends on what you want; it may not pan out that way for you.