This will be a long and fractured rant, most likely. I apologize in advance. But you did ask. The TL;DR is that medical school is a soul-crushing experience filled with uncertainty. For perspective, I go to a top 50, but not top 10, US MD program.

Your first two years are spent being force-fed volumes of information at a rate that you cannot even imagine. You think you can imagine it because you just kicked ass in a bunch of hard science courses in college, but you really have no idea. In medical school, I'd say you go through an university-level term's worth of information in about a week. The deluge just keeps on coming, and it's at a rate that discourages true understanding of the material. You'll be told that "the point is not to memorize, but to understand" but you will soon find out that the people who do well on the tests are the people who memorized everything.

Meanwhile, while you're eating your plate of pancakes every day and drinking from your fire hose, you will also be expected to jump, grinning, through an endless series of hoops. Peer learning sessions, mandatory group advising, skills labs, ethics reviews, and worst of all, interprofessional meetings where you will be told that healthcare is a horizontal team, not a hierarchy, even though it's very clearly a hierarchy. These various meetings will almost universally be complete wastes of time you should be spending studying or trying to schmooze your way into some research or other CV-boosting material, but will be required. The concept of "professionalism" will be used as a weapon to ensure your compliance, and the term will become so watered down as to become meaningless.

You soon realize going to class is a waste of time because half of the lecturers are PhDs who only talk about their research or ancient tenured professors who talk like the Ben Stein. Besides, everything is recorded. It's much more efficient to sit in the library and listen to the recordings on 2x speed

Now along comes your first licencing exam, USMLE Step 1. This $700 test is not a death-trap, but rather like a shallow hole full of punji stakes that you death-march towards for 12 hours a day for 7 weeks before deliberately stepping in. You see, basically everybody in US MD programs passes step 1. The problem isn't failing it, because you'll spend hundreds of dollars and hundreds of hours doing nothing but preparing for it. The problem is not getting a high enough score to become the sort of doctor that you wanted to be. The day-to-day difference between a orthopedic surgeon and a PCP is immense, but maybe you didn't get the orthopedic step score. Wanted to be a radiation oncologist? Too bad. An emergency medicine doc? Maybe in an undesirable location. By now you'll have 6 figures of debt and you're pretty much locked in, so hopefully you studied really hard or wanted to embrace family medicine already.

Now it's third year and you're excited to finally be out there, actually putting your stethoscope on patients and showing off that short white coat you got. Third year grades are critically important for your application, and so you want to do really well! Except that you soon realize that all the information you sweat and bled over is useless here. The knowledge from your first two years is almost entirely so that you can take step 1. Third year grades are mostly determined by the attending physicians and seem to be based on almost nothing at all. Seriously, third year grading is infamously arbitrary. If you go over to /r/medicalschool you'll see people stressing out about sitting down at the wrong moment or going into a room in the wrong order and it will seem ridiculous until you're there, and being kept up at night because you stood too close at the bedside and bumped your attending. You'll see some cool things, sure. But most of the time you'll wake up at 5:30am, come home at 7:00pm, and have accomplished little more than following your team around and nodding occasionally.

Statistically, it's somewhere around this time that most of the empathy will have been crushed out of you. Too many patients are self-destructive, or unappreciative, or too sick, or demented, or terminal, to actually care about them all. Besides, you have a note to write and hopefully your attending will read it because it's the only thing they're going to base your grade on (but they probably won't read it.)

Now it's fourth year and you finally get to pick some electives, but these are going to be mostly strategically positioned so that you can farm letters of recommendation for your upcoming residency application. Remember how shitty medical school applications were? Yes, this is pretty much the exact same thing except now you're also in medical school while you're doing it. You'll look up a million programs and apply to the vast majority of them for mostly arbitrary reasons. You just want to get in somewhere. Preferably somewhere nice, but the fear of not matching is real and tangible. You hear the horror stories of people who don't get into residency, and want to avoid that at any cost. Hopefully you're getting to apply into the specialty you wanted (see the Step 1 score discussion above.)