Amazon EC2 M4 and M4 Pro Mac Instances
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I would assume if it didn't take the enterprise world by storm, it would be enough sales for Mac only shops.
Except macOS and Apple's team doesn't seems to care about Mac anymore. They could have worked hard and attack the 1.5B Windows PC market and the few hundred millions of Chromebook market.
Instead it was all iPhone and Services.
The day XCode is made fully available on iPadOS, you can imagine where it ends.
The base model is great value but the upgrade pricing still throws that out of the window unfortunately. Just doubling the base RAM and SSD capacity doubles the cost of the entire machine, it's as if they're giving the SOTA processor away for free and making all their money on the storage.
In enterprise environments? Quite often on a 3-4 year schedule. Same with servers. (Yes yes, not all companies)
Usually most people get their iPhones via contract bundles, and they don't get new phones until needed, because that resets the two-year contract agreement where it is not possible to terminate the contract without paying back the full costs to the provider.