> assuming you paid for all 48 cores ($864)
...no, you're still reading it wrong. It's not the number of substrate CPUs on the compute node your workload is running on. It's the number of substrate CPUs on all the compute nodes your workload could potentially ever be re-scheduled or migrated onto. I.e., all the CPUs of every single (non-reserved) compute node in the datacenter. (Or, presuming certain service-transitioning technologies, multiple datacenters!) We're talking about e.g. "the entirety of AWS EC2 us-west-2." Hundreds of thousands of machines. Millions of CPUs.
By analogy: imagine there's a car-sharing service, that rents out its fleet of cars to people — but because, when you rent a car, you could theoretically end up driving any car in the rental company's fleet — they set their premium to be $18/mo * [the size of the rental company's entire rental-car fleet.] Because in theory, if you set things up just right, you could manage to drive all their cars, in one day. And so they want to charge you, at all times, for that basically-impossible worst-case upper-bound price.
Do you see how insane that sounds?