To be honest, I don't think you are that ambitious if you can't see any high-flying careers outside medicine. With medicine, the career progression is quite clear but even still only a proportion (quite high) become consultants due to rigours college exams and availability of posts.
With degrees such as biomedical science,biology, pharmacy... the career pathway is less defined so if you are ambitious enough, you can find yourself in a very well paid job. For example, a chief scientist in a government lab that I did work experience in was on £70k pa. It took him a long time to reach that post but it can be done.
So, don't be disheartened because there is still a good chance that you can use your ambition to secure a very good job in the future.