Even as a financially secure mid-career engineer this is still an excellent formula. Buy a "retired" Thinkpad on Ebay, upgrade RAM and NVMe if needed, replace battery if needed, then run it for a decade or more.
I started to see some poor-quality 'genuine' replacement ThinkPad keyboards. Bad action, bad fit of assembly with keycap catching on bezel, etc.
I considered it not-unlikely that no more good ones would be made, since Lenovo had stopped selling laptops that used that part.
So I stockpiled some good ones while I could, by sampling from a diversity of sellers. I wound up with 3 good spares, and 2 bad.
The workstations might have replaceable RAM but like apple some the x line and t line (I think?) have RAM soldered on so no upgrades :(