Medicine isn't always rewarding. Its all bright on the other side of the fence right now but frankly I don't think "we" can really make those types of assumptions. At least yet. You can want something badly but you aren't really exposed to medicine until your well into med school / residency. By then its almost too late to turn back with all the sacrifice. Shadowing / volunteering is good but its superficial.
My family has many MD's and I have spoken with many others. I like asking them . . . knowing what you know now, would you do it again? A high percentage say no way in hell. How you interpret that answer is arbitrary but the thought is provoking.
While what you say is certainly true, I think that both of our statements hold true. I recall reading a study that said that if asked to re-do their choice to become doctors, many physicians did say "no" (I don't recall which study this was, sorry... but I did read this). But, at the same time, their reason for not becoming doctor is due to a lot of factors - family issue, lack of not feeling satisfied/rewarded enough, disputes with insurance companies, and so on.
By the same token, some people HATE medical schools but they stick with them because they hope that actual jobs as doctors are different (and for some, actual job is better while it isn't for others). Similarly, there are others who LOVE medical schools and everything about them.
Medical school is not same as a college or university. You are not there to learn about what it feels like a doctor - no, medical school is a place where you learn
skills and tools for becoming doctors. That's why when you graduate from medical school, you are still not really a "doctor" because you don't know everything that surrounds your life as a doctor.
So, what should one do then? Well, the best thing - and really, the only thing - is to see what other doctors are doing, and think if you can spend rest of your life doing it. But, if you can't, then you may want to re-think, or maybe choose different profession later in your career as a physician. Many previous M.D.s go into health-care related businesses, and while many agree that patient-interaction is definitely something they'll miss, they are happy with their new choices. Everyone is different, and each person's choice is right on its own ways.
I suggest everyone to check out Doctors' Diaries by PBS. It will tell you some insights on how even the most successful students may not end becoming the doctors (or stick to them all the way through). And trust me, I've debated with myself for a long time and researched a lot into a career of medicine - it is rewarding, but it certainly has a lot of costs. It really comes down to what you want for your life (and for others to certain degree).