...ok, so flipping the y-axis.
I reckon that I do it because my first 3D game was Microsoft Flight Simulator (I haven’t looked this up but I’m pretty sure up and down are flipped in that game by default, like a real plane).
My brothers, meanwhile, who are all younger than me and had their first 3D experience on PS2/etc all prefer standard y-axis.
So what got you into flipped y-axis, if you use it? Something in real life that you were used to before getting into video games? One specific game that locked you into it?
As another old, this is correct. I think it's because until FPS games, the only Y axis games that I recall were flight sims, which defaulted to actual plane control Y axis. So we just got accustomed to it.