I have heard that the ethical man knows its wrong to do something. The moral man just doesn't do it.
That being said.
We all have different morals and ethics to live with. If a person can make the shot cleanly. I have no problem with it. Sure a deer can move in the split second it takes to travel 758 yrds.
But my 7mm Magnum covers that distance in less than a second. The bullet has hit the deer before the deer hears the shot.
The deer isn't going to move enough to affect shot placement.
Like super hunt said, most people don't have the time or space to practice these shots. There just aren't that many long range ranges to shoot at. That kind of space costs a lot of money. They have no business attempting shots like that.
I know my rifle after 20yrs of shooting it. But i know that i have no business trying past 200 yrds. That is my comfort zone.