Sounds like my boss. He's a PhD with zero respect for MDs and continually tells me how I'm throwing my life away, but deep down I can tell that he wishes he would've gone to med school.
Yeah, lots of people suffer from medschoolrejectitis, which for some reason, it still effects people decades after they got rejected. I've encountered quite a few of those folks in my day, and I can only pity them when they say stuff like, "I never really liked doctors. You're gonna lose a lot of sleep and being pre-med will narrow your undergraduate experience... yabba yabba..." I just smile and think to myself - I'll be outa this sorry job in a month but you sure won't! (evil internal laugh).
Seriously though, it's quite irritating when people openly criticize a significant choice in my life. I try not to take it personally. I try to let it strengthen my conviction in medicine.