If your main concern is salary which is completely understandable, then do not pick medicine. This isn't just because your not 'passionate' enough, but because there are just so many better, cheaper, faster more efficient ways to make a lot more money. Job security isn't as much of an issue now considering you can do a lot jobs remotely.
EDIT: a lot of people say that if your stuck on picking medicine and something else, it often better to do the 'something else'