@Marcel said
"So, is it possible to work as a salesman, making "cold calls" (uninvited calls to buissenesses) and be a Thelemite?"
Your word "possible" makes it possible to say Yes. It's possible.
But I understand the ethical dilemma. I could never do sales (or, rather, never succeed at doing sales) where successful selling was seen as bringing another to make a choice contrary to their real best interests.
Still, like all morality, it's gotta be an individual decision.
"Their wills being a Mystery to me i prefer to not "point the way" for people."
You can likely benefit from realizing that, in the event of true will, people aren't so fragile.
"I want to respect the paths of my fellow stars.
I also want to pay rent."
That's it in a nutshell! Both are worthy ends.