A 16" M3 Max with 128GB of RAM and no other upgrades would have been $5000 at launch.
They started shipping at the end of 2023, so you couldn't have bought a refurb.
Either you're remembering the price wrong or you got a crazy deal.
It's also pretty fucking sad how this thing comes with less RAM than my low-end Mac Studio from 2022. I only upgraded from a 512 GB SSD to 1 TB, and I still have 32 GB. And even still, I paid 2599€ for it, where as the OLED MacBook Pro is 4049€.