It is the physicality of it. If I think of it as simply a cursor I move up and down it does not make sense to invert. But I guess my mind connects with the physicality of pulling back to raise my gun or pushing forward to lower it. If I am not inverted I feel disconnected and the cursor just becomes a dot I move.

Inverting it is kinda like pulling up. "Pulling" on the stick, so to speak, naturally, it must go down to make you go up. Another example, the back of your head goes down, when you look up.

But, for myself, I want the direction to go in the way that I'm pressing. So, I do not invert.

No. I think it makes absolutely no sense in first-person games, but I think it actually makes more sense in third-person games. That said, I still don't like inverting it myself, even though I have experimented with it a bit. And just for clarification, I think it makes no sense at all to invert only one axis but not the other. If I invert an axis, I invert the other axis as well.

Yeeeessssss! And when a game has the y-axis already inverted as the default setup, I buy a second copy to help support the team.

Yep, always.

Never. Its uncomfortable.

For me, it absolutely does. The first 3D games I played were flight combat games on the pc, like X-wing and Tie Fighter. Ever since, my brain is trained to think pressing down goes up and vice versa. 

If you ever played a flight simulator as a kid, the Y-axis must be inverted for the rest of your life.

In games where you're flying I absolutely have to invert the controls.

I used too long, long ago but for some unknown reason I don't do it anymore, unless it's a flight sim.