Well, I think that depends on the person, but who says they are mutually exclusive. Most people find a compromise between the two. Besides an idiotic and untalented neurosurgeon can still make less than a talented, highly- regarded cardiologist, neurologist, etc. If you pick something you are good at and enjoy you can always find where the money is. In general though, I believe people compromise. If you like IM and ER and money/lifestyle is a factor, then the slight amount of more interest in IM may be worth forgoing to have a better career in another sense.