I hate it when people say that you are sacrificing your prime for medical school. Our life is not over after age 30. It just means we enter a new stage in our development.
Ok, I did the college-->job route. I partied and dranked and went clubbing until 4am....for about six month before it got old.
Yes, it's nice to have money and free time and be single, but after a few months of this, I realize it's all empty and meaningless. After a while, all the night clubs seem like they blare out the same loud music. Every bar seem to serve the same overpriced beer. After the initial thrill of partying it up, I realize I wanted to grow up and be an adult.
I decided on medical school after I got the partying out of my system, and while I feel a certain distance from my younger peers, I feel much more mature when it comes to handling medical school. I treat the four years as a job and I look forward to residency as another period of extended training.
Is the doctor route hard? Yes.
Will I get yelled at by my superiors? Absolutely (in fact, already done!).
Will I feel overworked and underappreciated? God, yes.
But is this unique to medicine. Hell, no.
To the OP, what you are experiencing is called reality.
Most people with who want to make real money (i.e >$80k) find that they have to deal with crappy bosses, long hours and sometimes an ardous path to that mythical promotion.
The unique thing with medicine is that it forces each "worker" through a standardized path to upward promotion. Therefore, I think of 3rd/4th year and residency as me working myself up the corporate ladder. My friends from college/work who want to see promotions and hit that six figures before age 30 have to work 60-70 hours/week. Many are forced to put up with frustrating bosses, and do scutwork. And while the upside is they get paid throughout this, there is also no guarantee that they will get that promotion (or maintain that promotion/paycheck indefinitely).
Medicine is harder than many other professions, but it also has its rewards. It sounds to me like you are perhaps not emotionally ready to accept the responsiblity that the route will force upon you. I don't say that in a mean way. I think I had the same problem when I was fresh out of college. But I got the partying out of my system in my job.
So maybe you should take a leave of absence and get a 'normal' job and enjoy your sabbatical. Perhaps after a year of traveling/clubbing/drinking, you will be more focused on medical school. I know my tenure in the work world made me a better student.