There isn't much knowledge in rocketry that's actually unique to
rocketry. Basic physics and chemistry is applicable in every other
form of engineering too; it's the foundation of them all. When you
have an opportunity to learn from someone really good, do so even when
it's not directly applicable to rocketry; such opportunities are rare.
Careers are a matter of economics: you want to be providing a skill
that's in demand at the moment, and that depends on what the outside
world is demanding. What demand for rocketeers will be like a decade
from now when you're looking for a job is hard to guess. In every
business there are cycles of interest and demand followed by
oversupply and jobs being hard to find, so don't be too dismayed if
you find you're making another use of your skills. You might even get
sucked into a place like this:
https://www.youtube.com/watch?v=acbnyagl8jo
"So you're a rocket scientist?"
"I was."
"Interesting. How did you end up here?"
"It's all just numbers, really; just changing what you're
adding up; and to speak freely, the money here is considerably
more attractive."
That's not making a recommendation -- those people were _not_ having
fun, and from a societal point of view were causing a great deal of
havoc -- just saying why it's hard to make a recommendation, and why
it's safest to learn core skills and be flexible. Yes, it's a movie,
but the phenomenon of people with good math skills getting sucked into
finance is quite real, and was especially prominent around that time.
The havoc was also quite real, though of course (as Wernher von Braun
could tell you) one can also produce havoc by being devoted to actual
physical rocketry.