Amen to brother Ed's comments above.
I'd like to add that other professionals tend to view documentation as a "necessary evil" -- not an integral part of the product, but a way to legally protect the company or to provide caveat to the product's supposed abilities.
In my 11 years as a technical writer, I have unfortunately only felt esteemed a few times. Most of the time other professionals avoid me because I represent one of the facets of their work they want to ignore: documentation is a painful extraction of information.
This is just and true fair warning of you plan to be a tech writer.
Advancements depend on the company and the location. I used to make around 70k in Cincinnati and got much training in project management and writing seminars, STC, etc. Now I am in Louisville, KY (past four years) and only make 53k and have had no training or opportunities to advance except into management -- yikes.