'Graphic design' is a broad term which is basically useless in defining the actual careers of graphic designers. 'Graphic design' really involves multiple career streams and in most cases many different forms of media. This is such a gigantic commercial market, and graphic designers are so much in demand that the career tracks need to be mapped out.
Graphic design is a formal study, but talent and preferences play a big part. Graphic designers are highly motivated people, and their areas of specialization can vary a lot. Many graphic designers also study media, fine arts, CAD design, and a large range of different types of media.
Qualifications do matter in graphic design. If you check out the employment market, you'll notice that there a lot of specifications written in to the job ads. These are all production-based qualifications, and they're all relevant. (These job ads are always useful for checking the job market.)
One of the big advantages of a career in graphic design is that skills are very portable, and 'job agility' is a big part of career moves. Whatever your area of expertise, there are other issues, too. The employment market in graphic design is huge, but demand for current experience in specific parts of design and on major software platforms is also extremely important.
This means that graphic designers need to keep an eye on their job and career options. Most graphic designers work in either an organization or on a contract basis. Employment can relate to job availability, and the 'portfolio factor' in this employment sector is critically important. This is a highly competitive field, and being able to show high value skills and experience is extremely important.
Another issue for graphic designers, particularly freelancers and contract workers, is managing incomes. The income stream can be erratic, and it's important to learn the finance management and business skills. Contract management in particular requires care. Steady income streams can provide a lot of increased capital to fund expanding business and increased production capabilities.
If you're truly highly motivated and your love of the arts is your greatest joy, graphic design is a good choice of career. Talent matters in this career dynamic, and this truly is a global market. You can go a long way in a hurry as a graphic designer, if you know the market for your work.