I was in a similar situation as you. Computer Science major in undergrad. Worked for 2 years in tech consulting. I was probably one of the overpaid peons who worked underneath you.
I quit 2 years ago and I'm entering med school this fall. My reasoning was much the same as yours. At the end of a day at work, I returned to my posh apartment, and all I had accomplished was X number of scripts. I was in fact, spending my time making rich men richer, and they in turn were paying me for that. I had sold my soul for an apartment full of Pottery Barn furniture. That didn't sit well with me - and I knew I was on the fast-track to mid-life-crisis and becoming disgruntled middle management. After all, you only get one life, and I wanted to feel like I'd done something with it besides hoard large amounts of money and buy myself stuff.
I won't lie to you. Losing the salary is hard. Losing the Manhattan apartment is hard. It's even harder when you're woken up one morning by your cell phone going off, and its your old coworkers screaming about the 20k bonus this year. There were mornings when I'd wake up and stare at the ceiling and wonder what the hell I was doing here. But then again - where else do you find a job where even on the BAD days, you can say "I helped X number of people". Where else do you find a job that's so essential that its been filled by generations of people before you - shamans, medicine men, healers, and now doctors. You will never be a victim of the economy because people will always be getting sick and women will always be having babies. Where else do you find a job that gives you the fuzzies of being a do-gooder AND a comfortable salary? People may argue that doctors are making less these days than they were before, but I argue that they're still making more than the general population. Even a family physician (the lowest paid) make 6 figures. You can definitely live comfortably on that. Lastly - how often will you get a chance to go back and do things over? What prompted me to quit so suddenly was the realization that the longer I waited, the harder it would be - for exactly the reasons you stated. I would be too comfortable. I'd get promoted and it'd be harder to leave (incidentally, I got promoted a week before I gave my 2 week notice). I'd have a family and then would be trapped by a mortgage payment. If you're gonna do it, you should do it NOW. It may not be an ideal time, but the longer you wait - the less and less ideal it gets as "surprises" pop up (kids, house payments, etc.).
I'm going to go out on a limb here and disagree with what a previous poster said. I think you DO have clarity. What it sounds like to me is this: You've decided you want to go to med school and you're willing to make the financial sacrifice for it. The thing holding you back is this vague notion of "Am I being impractical? Everyone else thinks I'm stupid for giving up a perfectly comfortable job" and a sense of guilt towards your wife. And you're scared, because quitting your job means going into the unknown with no assurance of success (i know the feeling). You can either stay practical and remain with the status quo - which you're right, includes a nice job, a future house, etc. But don't forget that this status quo also contains discontent. Will this discontent grow over the years like your mortgage payment? Or are you relatively sure it will stay small and you can handle it? Even more importantly - will your decision to NOT pursue medicine due to a sense of obligation towards your wife lead to resentment? Hopefully not. Venturing out into the unknown is scary - but it potentially also holds the reward you want. Like most things in life - there are no promises, but there are people who've walked this road before you and made it. So take heart in that at least.
The older students I met were infinitely more satisfied with their med school choice than the fresh grads from college are. The reason for this is because they've usually explored medicine much more deeply, heavily contemplated the sacrifices needed, and mostly - because they have perspective. It's important that you do this also. Medicine isn't going to be the answer to everything, you're not going to love it every single minute of every single day. Let's face it - a job is a job. It pays the bills. But if you're going to have to spend 2/3 of your life at a job making money, it may as well be one that will bring you a little bit of personal satisfaction.
My suggestion is this: talk to your wife. Because there's two of you, she'll have to be supportive of this as well. I wouldn't sacrifice my marriage for medicine, just like I wouldn't sacrifice my marriage to ANY job. Then, do what you feel is best. Screw practicality - it shouldn't even be a factor in this decision. You can spend your entire life being practical and be utterly miserable. You're the one who has to live with your life, so you should do what you think is best - whether that means pursuing medicine or staying in your job.
This is easy for me to say because I just walked this road and I made it to the other side when I got into school a few months ago. For me, it paid off, and it was worth it. But, it doesn't mean I forgot how frightening the uncertainty was, I didn't forget my parents disapproving deeply of my decision (why forgo security and go into debt for something you're not even assured of?), I didn't forget all the advisors doubting me, and my friends thinking i'm crazy. There's a thread around here called
IT to Med School . Look for it. Think long and carefully - because this road is long and hard. And Good luck.