Two things.
1) The "internet review phenomenon"- No matter what people are reviewing online- restaurants, doctors, jobs- keep in mind that people are motivated to make accounts and write reviews not for average experiences, but for great experiences and horrible experiences (usually the latter). This is great to keep in mind for SDN- the average med student who had a decent med school experience, and the average physician who has a decent job, are not statistically the most likely to write on here- instead, you get the "horror posts"- remember that these are a very small sample.
2) The "hindsight is 20/20 phenomenon"- (DISCLAIMER: I'm going to relate this to my basketball career. I know that medicine is not like basketball. I know that you can't save people's lives with basketballs. I get it. This is a metaphor.) It's easy to look back on decisions in life and laser-focus in on regrets. However, some of these doctors may be unhappy regardless of career- they have a rocky marriage, they spend beyond their means, their coworkers aren't as sexy as they'd hoped, etc. But I like to relate this to my college basketball career as well, because those four years were a f****** grind. The early workouts, crazy coaches, working to the point of mental and physical exhaustion. I don't tell people not to do it, but I tell them to make sure they really want it. Because despite challenges beyond what I thought I could handle, I absolutely LOVED playing. I loved the challenge, the camaraderie, meeting high goals. I still cry when I watch buzzer beaters on TV because I remember the feeling. Would I have avoided some horrible, hard times had I not played? Probably. Would it have been a better life choice for me? Probably not.
TL;DR- The internet is a cesspool where people come to complain, with some true valuable gems of info floating in it. Don't disregard the negative info, but contextualize it and realize you likely have a skewed sample
Edit: Also, for the MCAT, SCHEDULE BREAKS. The benefit of reviewing the amino acids one more time never outweighs the benefit of a much-needed mental break. I took Friday, Saturday, and Sunday nights for myself and my housework, and my score did not suffer for it.