At my school, you can earn a $7500 academic merit scholarship for finishing in the top quartile, and there are additional merit scholarships available for performance on specific coursework throughout the year. It's difficult but not impossible to earn almost 10,000 a year just by getting good grades in the preclinical years.
When I learned that, it really settled the question of whether I was going to get a side job. Doing well in med school is my job, not just in the figurative sense that it takes a lot of time, but in the literal sense that I can (potentially) earn money.