When Friends is brought up in conversation, Rachel's career is rarely discussed – only ever in the context of going after Ross for his disrespect for his girlfriend's career and autonomy. While well-meaning, this essentially means that even feminist fans of Friends are trivializing Rachel in the same way that Ross does.
Rachel's career is unique within the context of the 90's sitcom because she, unlike the other friends, begins the series unemployed and with little to no working experience at the age of around 25 or 26. By the end of the show, she is so successful in her field that she is offered a job in Paris, the height of success in the fashion field, to be quite honest.
So already, there is a huge amount of character and skill growth within just a decade. But even looking at each year individually, it's absolutely amazing to see what she accomplishes.
She begins working as a waitress, typically very poor due to her lack of skills (resulting in minimal tips), as well as the minimum wage associated with waitressing. But another major reason for her consistent lack of money was that she was addicted to shopping as a result of her formerly lavish lifestyle.
After approximately 2, 2 and a half years of waitressing (again, her only known job experience), Rachel gets a grunt job in the fashion industry (which she had expressed great interest in joining many times before), and begins slowly climbing the ladder, eventually becoming an executive at Ralph Lauren. While a big reason she can do that is because she makes connections and is very personable, making it easy for her quickly move ahead in life, it is also because she genuinely has knowledge about the brand from a time she would rather forget due to personal guilt and shame about the person she used to be, as well as acknowledging her previous issues with shopping.
Rachel, rather than trying to make herself a whole new person that she could barely recognize, harnesses everything positive about the selfish, wealthy woman she was before, and utilizes it to make a new life for herself based on hard work and what she loves. Her love for shopping is no longer a coping mechanism for discontentment, but instead is a way of trying to help out her friends, like when Joey was preparing for an audition.
And no matter how often her career is put down by people (specifically Ross), she never stops believing in it as her calling and works hard and cares about it so much, attending conferences even when she was very low in the field.
And while it's never really called an addiction, it is implied that, based on her sisters' habits, before her life in Friends, Rachel was not particularly mentally well or sound, and shopping was used as a symptom of the issue. It is honestly inspiring to see her take her former weakness and turn it into her greatest strength.
All in all, as problematic as Friends is in contemporary times, the way that it deals with Rachel's reinvention of herself and her goals is incredibly well-done, and gives hope that for people dealing with all kinds of issues that they don't have to get rid of everything about themselves, they just need to stay strong and make their weakness that strength.