Two points to remember. You actually have to do really well at high school to get into a medicine degree. You also have to study incredibly hard to graduate.
A CPL course will take almost anyone and will keep you repeating things until you pass or run out of money. Medical school won't let you do that.
When you get a CPL your qualified to fly pretty much nothing bigger than a 182 and that's it.
Medical graduates have a wide selection of career paths that don't necessarily coincide with treating human patients.
A medical degree is a bit more of a meal ticket than a CPL.