And this applies also to those who specifically studied to be , e.g. a teacher. Best teachers, singers are those who took up the minor job because the needed to survive.
Best translators are those who studied a more interesting subject and who became translators as means of survival; because is hard to survive on things that interest no one, e.g. anthropology and such.
The good thing is that this "translator-as-a-second-profession" not only knows how to better get clients but also might even provide better translation (especially in certain subjects). He has more "life experience" or deeper insights, which will show in his rendition.