If you are thinking about an MD, you are not averse to post-bachelor’s study. Biology is a good base on which to build a large number of medical careers (not just MD, but various ones which require less years of study than an MD: Physician’s Assistant, Physical Therapist, Occupational Therapist, Chiropractor, Optometrist, Dietitian, Pharmacist, Dentist, Clinical Laboratory Technician, etc.), as well as, through advanced degrees such as MS/MPH/PhD, careers in health or biological research.
The United States ABOUNDS with Spanish speakers. And I have observed that almost all of the resumes of people seeking interpreter/translator work on Indeed.com are of native speakers of the non-English language entailed. If you don’t teach, but you would like to do one of the medical or research careers I mentioned above, biology will serve you much better for building career-relevant knowledge than Spanish. Yes, it is good to be English-Spanish bilingual if working in a region with a lot of Spanish speakers, but one doesn’t need a whole degree in it to reach conversational proficiency. In fact, in my experience the process of learning Spanish from Spanish-speaking neighbors and following Spanish language TV is more appropriate in outcome and vastly more efficient than the academic process.
Instructors aren’t disinterested parties. Instructors in a field have a vested interest (whether they consciously realize it or not) in seeing their choice of field vindicated by others following suit and also in building “clients” (students) to receive their services and thereby confirm the validity of the instructors being at their jobs.
To be fair, perhaps I am a little biased the other way, having majored in science (chemistry).
I don’t, because sometimes you can’t get work doing the thing of your passion later on and have to make do with whatever work you can get - which you may not like anymore than the job-practical, but uninspiring, majors previously spurned. In those cases it’s hard to be very happy. Therefore, while passion is worth some “points” in the choice of a major, employment prospects need to also factor in the choice.