I see your your point, but I only have one shot at a mission, too give it my all, while even if i get fired i will always be able to find a new job, receive help from family, or the Church. I would say that a mission is more stressful because i have the wonderful opportunity to bring the gospel into people's lives and if i don't go or don't work 110%, i miss out on blessings that will impact others and myself way more then a job would.
I guess i do agree its the expectation that is hard sometimes. If you postpone i feel people think you are a looser and a sinner.