See Medicine is a fast field but MBBS is just a tiny part in it. One can do Bachelors in any of medical fields like pharmacology, nutrition, neuroscience and even management on public health policy, hospital adminstration. 

Coming to knowledge and good salary, each field has its own set of knowledge to be acquired which is fast and cannot be comprehended in own life. For salary, even MBBS graduates have very less 30k to 40k salary after 5.5 years of training. Money comes with age and experience irrespective of which field you do. 

I would recommend you to choose the path you feel passionate for, knowledge and money will come with it if you be good in it.