I'm not getting my main point across.when I specced them so the base iMac
When someone orders a Z4 - they don't look at matching the iMP specs.
They look at building a system that meets their needs.
They may already have a good 4K monitor, and don't need to add an extra 1TB NVMe disk to compensate.
They may need 4 cores, they may need 18 cores. They may need 16 GiB of RAM, they may need 256 GiB of RAM. They may need 10 GbE networking, or they may be in a 1 GbE environment.
These price comparisons that try to match spec for spec (even without the ludicrous bit about adding a 1TB NVMe disk to offset the monitor that the user might not need) are horse feces.
If you need exactly what Apple provides in their config, the price is not out of line. If the config isn't right for you, or you want some freedom to upgrade - get a Z.