Not a gamer as such apart from "I've played some computer games at some points in my life". I don't know about the current generation(s!) of gamers, but in DN3D and Quake when "mouselook" was first added, the default was what "inverted" as in forward = aim down. Then "invert mouse" was added that made it "normal". I did very little flight sims but I played quake, Q2, Q3 and Half-Life this way (forward=down), possibly also HL2 and I can't remember why, then I switched. My best friend from school also played this way. I honestly don't remember how it started; I always thought it was because that's how I first played.