In the trenches they had rats, lice, cold, mud, the constant stink of death, and that was just their daily existance without the extras thrown in by combat, gas, artillery, small arms fire of all sorts, trench raids, and you could be burned to death in the trenches too, they had flame throwers in WW1 also.
If you were flying most of your time was spent in a lot more plesant surroundings, until the grim reaper made his call.
One of the memories of my boyhood was one of our local WW1 veterans, Chant Kelly. His description of living in the trenches was vivid.
He said take you average outdoor privy ( do you city boys even know what i'm talking about ?) get down in the hole, live, eat, and sleep in it for a couple of weeks, that's what the trenches were like sometimes. A level of filth and misery most modern people can't even imagine.