Seems like they just come on board, close the door and do there thing without ever seeing or thinking about the 400-500 souls a few feet away who trust them like a brain surgeon.
Well, you can't think of the responsibility like that. It would totally jinx you. That's true in any job. When I was a stock broker I sometimes lost money. It was part of the job. No risk, no reward. But you can't let the fear get to you. Note, I don't mean by that that pilots sometimes make big mistakes
, just that responsibility is part of a job and you get used to it.
Piloting a commercial airliner is a technical and challenging job, but it doesn't require a superhuman, just a very highly trained human. As in anything, practice makes perfect. If you do it often enough, it becomes second nature.