Paying an additional $720 to upgrade to 1 TB when a 1TB NVMe SSD goes for $400 seems ridiculous. But I really have no problem with that price gouging, as long as one can rip the thing apart and upgrade it on one's own.
Where? I've re-read your post several times thinking that there must be some mention of NVME vs SATA somewhere in it that my eyes are just skipping over, but I can't see it :S
Samsung 860 EVO 2.5" SATA III 2.5in SSD, 250GB $109.99
Samsung 860 EVO M.2 SATA III SSD, 250GB $109.99
Samsung 860 EVO Series mSATA SSD Solid State Drive, 250GB $109.99
Samsung 970 EVO NVMe M.2 PCI-E x4 SSD, 250GB $129.99
With greater capacities, the price difference gets larger. But at 1 TB it is still less than a factor of 2.