Regarding your financial concerns, medicine is a very safe investment. You invest ~$250k, and your return is a stable job of a minimum $250k/year for the rest of your career. Salaries can be much higher depending on which specialty you go into ($300k-$600k.) The graduation rate and match rate is high for USMD students, so I wouldn't let concerns about the financial ramifications of not graduating/matching affect your decision too much since both are rare occurrences and generally avoidable.
Regarding debt, unless you have family support, are independently wealthy, or are a super impressive applicant that can get a merit scholarship, loans are a reality of this path. That said, there are several loan deferral/forgiveness programs available, and you can structure your repayment in many ways, so your loans don't have to be a burden on your life.