I'm a pre-med, but I'm non-traditional. I've held three full-time, Career (with a capital C) type jobs in my life, and I'll chip in my thoughts. They're mostly pro-medicine (hence my pre-med status).
1) Most jobs have just as much BS as medicine. Whether it's endless meetings where you mainly sit and pretend to listen, or extra time spent explaining your "Long-term career goals" to your boss, many jobs have just as many boring, inane activities to complete as filling out insurance paperwork and charting/dictating. Unless you open your own small business, you'll likely be stuck with some of this everywhere you work.
2) The entire idea of "wasting your 20s" is largely a fallacy. I believe that some people who went directly from college to medicine envision their 20s and their first job as this great time when you essentially continue the party lifestyle led in college. Many for some people this is true. But for most, it simply doesn't happen. Everyone settles down somewhat after college and there are many fewer parties and hanging out. Soon people are having babies and hanging out even less. It's sad, but that's just life. I actually think med school helps prolong the partying because you're still in school for another couple of years. You work hard, but you can play hard too, if desired.
Plus, most Career jobs require you to work more than your strict 40 hours if you want to get ahead. Expect 50+ hour weeks indefinitely if you ever want to be promoted to VP of whatever. Americans see your value in a job by how much time you're there. No President of any company (self-employed or not) works his/her 40 hours and goes home. It just doesn't happen. On the plus side for medicine, once you're a full attending with a few years under your belt, you have more flexibility in terms of working a schedule you desire. If you choose your specialty and practice environment well, you have pretty large control over your schedule. This is pretty rare in the corporate world. No VP of anything is working 3/4 time to spend extra time hanging out with his/her family.
3) There are rude/egotistical people everywhere. Sadly, medicine does seem to garner a larger than normal amount. I think this is because everyone in medicine is quite intelligent, and many people have an inflated sense of self because of it. But, I've been yelled at by people in several of my other Career jobs. There are people who suck in every walk of life, and you can only control your actions & reactions, not anyone else's.
4) It's harder to switch careers than many people in medicine believe. I have a Master's degree in statistics. I worked as a statistician for 1 year before doing my post-bac work. I started looking for a job this past spring. I got literally no response from about 50 applications for research assistant positions and no response from dozens of misc. applications. I eventually got a 3-month contract to be a Production Assistant. The pay was less than 1/3 what I had been making as a statistician. A statistician position came along in the city I was tied to, and boom. I'm a statistician again for this year. First, yeah, it's a terrible time to be job hunting, so that's holding me back. But, you're much more strongly tied to what you got your education in and what your experience is in than some medical people give credit to. Switching Careers has a huge transition cost associated with it that most people with a family can't sustain. Further, there's no way to get any sort of engineering job, business job, etc. without getting more education in the form of a BS or MBA degree. It just doesn't happen. No one's going to hire you without proof that you know what you're doing. The job market is less flexible than some people believe unless you're willing to go back and train more.
So, for me, I'm going into medicine with my eyes wide open. I've shadowed a bunch (both academic and community docs) and done a good bit of health-related volunteering. I'm going into medicine expecting there to be some of the same downsides as most jobs. But, for me, it will beat sitting at a desk for 8-9 hours a day and fiddling with data on my computer. It also beats any other option I've come across as a realistic (for me) job opportunity. Would I enjoy being a professional photographer or writer and making millions? Sure, probably, but that doesn't happen for many people. It would probably never happen for me. Medicine can and is a decent 2nd place.