I started using personal computers in the 70s. Dad brought home a series of systems: several different TRS-80 models, several Apple ][ variants (including one of the units that were in the "sign up to buy when they become available" ones) and others. Our first x86 box was a first-edition model, as well, and was beastly heavy.
In addition to the personal computers my dad brought home, he also opened a small software company. He had a few Altos systems that had to be access via Televideo terminals. It was in working with these that I settled on the -on-black style for my terminals (very few systems did other-than-black backgrounds β CRT that didn't have a black background that I encountered wasn't until I walked into my university's Sun lab in 1989(. Those Televideos were all green-on-black (vice, say, the old Wyse terminals which were all β at least any of the ones I worked with β amber-on-black). As a result, my go-to color-scheme for terminal-sessions is green-on-black.
During my first gig as a Unix administrator (overseeing a mix of Sun and SGI workstations and servers), I discovered that I could more-easily avoid sending commands to the wrong systems by assigning each system I logged into its own -on-black scheme. To this day, whenever setting up a new terminal, I use green-on-black as my default and then set up other -on-black predefined sessions within whichever terminal-emulator β mostly #PuTTY β I'm predominantly using on that system.