First thing that I would like to say is, choose the path on which you think you will be able to walk. What I mean is, you cannot make a career decision by sitting idle and thinking for an idea and you get an idea you think that ok I will be doing this. If you want to open a coaching institute without investment then yes you will have to be a great teacher. Once you make a face in the crowd and gain momentum of students flowing in then you can think to hire other teachers and then invest in taking a space etc.
Hope my reply is relevent to your question.