When it comes to work that will build a great career, Patrick McKenzie has great advice:
Profit Centers are the part of an organization that bring in the bacon: partners at law firms, sales at enterprise software companies, “masters of the universe” on Wall Street, etc etc. Cost Centers are, well, everybody else. You really want to be attached to Profit Centers because it will bring you higher wages, more respect, and greater opportunities for everything of value to you.
The gist is that you want your role at the company to correlate with revenue generation.
If your role leads to more revenue, your role will always be in demand. Sales functions have so much money allocated into them with the expectation that it is an investment. Back office tasks (HR, accounting, etc.) are essential, but they do not generate gross revenue and are always on the chopping block.