[Hypothetically] Imagine a small 4 person B2B software business doing fairly well. To get to the next level requires more exposure and sales.
Imagine you can afford to hire one more person. Would you:
Hire a marketer to try and focus on content marketing, reaching out to bloggers, SEO, advertising placements, etc, etc,
Hire a sales person to follow up on leads (people that have downloaded and left an email address), and perhaps drive new sales in other ways (cold calling? attend local meetings? etc?)
Which will increase sales enough that you can then hire and grow more?
In this hypothetical situation the niche is huge, and the small company is almost unknown.