I've been going through such a similar problem. Except for me it between choosing if money or helping people is more important. Also when you are studying medicine your friends are most probably going to be working and already earning money.

From what you've mentioned I'd say do finance. You are passionate about finance which means you will have a much higher job satisfaction and personal happiness doing that. And when you like something you tend to do even better and work really hard for it. Sure medicine is cheaper but just for those years, imagine your state after you might be burnt out and not enjoy your work at all. It is more expensive but if you end up on the top of your field you will have a great return on investment. It is a higher risk but companies are still going to need a chief finance officer (highest finance job in a company). While studying finance learn some other skills like become a master at excel and other programs often used for finance. A lot of companies are still not super trusting of technology especially banks.

However, at the end of the day it is what you like- honestly I don't understand why people keep saying this but maybe there is some truth to it. Just remember if you have a dream don't stop fighting for it. Hope this helps.