It really depends on where you want to see yourself doing. For example, if you want to enter investment banking or venture capital in the healthcare space, this background might come in handy. Or even, if you (in the long run) decide to get into hospital administration, knowledge of finance will come in handy. Business knowledge is useful regardless of you become a doctor or not. If you just want to become a doctor and don't want to apply the knowledge, you don't have to know it. In my opinion, marketing or management are more applicable than finance if you want to be a doctor.
And it might increase your chances of getting into medical school. Finance/marketing are not a common major in medical school.