It's not just that I-banking is hard work, it can be demeaning and stressful.
My friend who is an i-banker interviewed at Goldman Sachs and they asked him in the interview what he would do in this situation: It's the day before his brother's wedding, and he is supposed to be the best man at the wedding. But there's a big deal that's about to be closed at work, and his boss asks him to skip the wedding to make sure the deal is closed. What would he do?
Of course the right answer is that you skip the wedding.
I-banking can dehumanize you. When all you do is work and sleep, there is nothing left of you. There is no "you" left, just the you that works, and the you that sleeps. The people I know that have been doing i-banking for years have totally lost touch. It's almost like they've lost social skills in the sense that they'll say really tacky things in mixed company because they're so immersed in this money-culture that they think it's socially acceptable to constantly talk about money and how much everything costs and how much people's salaries are.
Not to be overly dramatic, there are obviously exceptions (and I'm mostly talking about i-bankers in New York which is probably way more intense than anywhere else), but by and large people easily lose balance in their lives if they stick with i-banking.
BUT, everyone posting in response to your main posting here (me included) seems to be making the assumption that you would be disturbed by this. But from some of your replies it sounds like money really is the most important thing to you so maybe i-banking would be a good field for you. (I really don't mean that as a slight, I think most people in i-banking would flat out tell you that money is the most important thing to them).