Stress
Up before dawn? Check. Ridiculously long days? Check. Little time off, no certainty about next job location, managing a crew, and arguing with directors? Yeah, you've got all that covered too.
While there are definitely more stressful jobs in filmmaking, there are just as many that are less stressful. On the Stress-O-Meter (it's a real thing, we have it in our basement), directors of photography land somewhere in the middle.
Then again, other people might go home after a stressful day and relax while watching a movie—but watching the cinematography of others might also stress you out, so you have to account for your potential stress-relieving activities, too.