Haha, man I'm getting murdered. I wanted to elaborate more in my original post but didn't have much time and figured I'd at least put that much up to see.
I grew up wanting to be a doctor and actually entered college Pre-Med. I took a finance class freshmen year and found it easy and entertaining and decided to switch to Finance. I graduated with a 3.8 GPA and had a job with Investment Bank all lined up by the time graduation rolled around. I unfortunately did not consider what the work would be like in my field of choice. All I concerned myself was how much $$$ I'd make. I obviously regret my decision considering I'm here on this message board.
I have been volunteering/shadowing at a local hospital for the past few weeks trying to get a feel for if this is something I could do for the rest of my life. So far, I love it. I want this to be an informed, well thought decision and so far all signs point to me going for it.
I have learned a lot about myself the past two years, most importantly that I genuinely enjoy helping people. I tried to convince myself as my college career came to a close that I would enjoy Investment Banking because of the money. How much money I make is easily one of the least important factors for me and my career.
The reason I asked for someone to convince me to stay in Investment Banking is because all I have heard so far is how great a career in medicine is. I want to hear someone tell me how terrible and soul crushing it is and spare no detail. And when their rant is over, I want to be able to say and truly mean "That's what I want!".
I didn't read your latest post carefully. Apparently you are already shadowing. Well, continue that and go deeper. Observe and form your own opinions based on your experiences and also what you hear from experienced docs you are working with.
In terms of the negatives, medicine is just like any other job, really. There are similar aspects it shares with other professions. Since you are already a professional, these aspects won't phase you so much as the kids entering medical school who have never held a real job.
However, I think one of the most frustrating parts of being a physician (in my imagination, anyway) from my own personal experience in rotations, at least from a primary care perspective, is that you have to deal with the multi-headed beast that is the American insurance system. It is sometimes a daily fight against these behemoths to get what you need done in just the way that you think it ought to be done for your patients. These giants like to tell you how to practice medicine and like to pinch every penny, nickel and diming everything. It can be very frustrating at times and you may not get the reimbursement you thought you would. Third parties often decide how much you get reimbursed and they are just looking for opportunities to not pay you, or pay you less. These companies put their pocketbooks first, not the patient or you. Not only that, but sometimes patients can be VERY demanding...it's a service industry and sometimes you feel like you have to cater to them and their sense of entitlement. It seems like, at times, that everyone is trying to tell you how to do your job. Then there's the encroachment of the midlevels and increasing popularity of non-evidence-based practices, but I won't even go there. And then there's the time pressure component.
Another negative is the incredible amount of training required just to be a licensed, competent physician. It's a long, challenging road and there are a lot of hoops you have to jump through, some of which are redundant, frustrating, or make no sense. At times, it can seem endless and you can't very well see the light at the end of the tunnel. Just when you think you are done, there's years more. If you don't have a deep love for what you are doing, it's going to hurt all the more.
As a non-trad with a non-science degree, you'd have to go back to school and take all the premedical prerequisites with all the kids, and not just do well, but ACE them. Then, you have to take the beast that is the MCAT, which, even after all this time, still seems like the most difficult test I ever took. You have to ace that, too (or do as well as you can). Then you have to play the game of getting into medical school, which is very formidable. Once you get in, assuming you do get in on your first try (or at all), you have to study your ass off everyday in some dark room while all your peers are living their lives, or spend endless hours in the anatomy lab smelling like formaldehyde (you can't get that stench out of your cloths, and even now, I can still remember that smell). The first two years of medical school are very challenging, even if you are smart. In medical school, EVERYONE is smart. You have to have good study skills and be very diligent. Even then, you could still end up in the bottom 50%. Then you take Step 1, which is doable, but still very challenging. How well you do on that important test has a great impact on your match application. It's a high-stakes test. After that, you rotate in hospital and clinics as a clinical clerk, which means you are at the absolute bottom of the hierarchy. I think even the janitor has more pull than you, as a clinical clerk. Medicine is very hierarchical still. It's long hours of trying to learn as much as you can, with no authority, and sometimes abuse, without any pay (actually, you pay your school for the opportunity to work, as twisted as that sounds). To make matters more difficult, grading can be highly subjective. Meanwhile, you have to keep in mind that this is a clerkship and you have to appear to want to be there all the time, eager and hungry: "Yes, Sir, can I have some more!" Then you take Step 2, which is easier, but you still sweat it, because you have to pass and do reasonable well at least (moderate impact on your match, but more important if you didn't do well on Step 1). Somewhere in all that stress you have to figure out what you want to do for the rest of your working life. As you enter fourth year, you get recommendations, do your match application, interview, do audition rotations, etc. The match is VERY stressful. After that is done and you match, you then have to do a residency, where you again work long hours while trying to learn as much as possible, but this time you do get paid, but it's not enough for the hours, abuse, and huge loans you now owe. Somewhere in your internship year, you have to take Step 3; this time, you just have to pass, unless you are considering a fellowship. Eventually, you finish and get to be an attending physician and enjoy the fruits of your labor. Like I said, a long and difficult road.
If you don't have the heart for it, I imagine it will be extremely difficult. It will rob you of your soul for awhile. I think it took years off of my life and I haven't even started the most difficult part yet (internship year).
Another negative I can think of is the cost. Most of my colleagues are $200K + in debt from student loans. And it's compounding. I don't have to tell you how much that hurts, since you are a finance guy. This can be extremely stressful and it makes your budget very tight during residency and perhaps later, too, if you end up in a specialty that doesn't pay as well as some others.
That's all I can think of now.