If you have the talent and dedication, you can prepare yourself, and if you already have an undergraduate degree, perhaps get into a master’s program, most likely music education. What might be feasible is that by the age of 32 or so, you will have learned enough to teach and perform, and you might go to a country where they do not really have a professional harpist and build up a community there, or in part of this country, though few areas are left without harpists. To be a top-flight professional performer, you would need to be extraordinary. However, if you are interested in alternative music, the doors are wide open if you come up with a unique approach.