Question: Why do most programmers/developers use a dark theme while writing software/code?

Answer: Because light attracts bugs.

@nixCraft

Easier on the eyes...

Prolongs the life of your LED screen, particularly if it's OLED.
@ferricoxide @nixCraft It’s actually from before LED screens, CRT screens had a hard time providing non flickering white backgrounds.
Which is why I find it weird that people choose dark today, proper white works just fine now.
@helge @nixCraft

Having been using computers since the 70s, always found most of the modern "light mode" implementations to be eye-searing. Irony is that the display Postscript systems of the late 80s and early 90s were less fatiguing than the 00s' eye-burners. Probably a function of the difference in light quality produced by cathodes vice LCDs and LEDs.
@ferricoxide @nixCraft I’m not entirely sure what DPS has to do with it, it’s a display hardware thing. I’ve been working with NeXT MegaPixel displays and they’ve been great for the time, but they can’t rival the cheapest LCD available today.
I think eye strain is primarily because they are too capable, tune them down 🙃
ePaper displays are the real contender.