Let's assume we have a staff of 10 and they're fully allocated to committed features and deadlines, so they can't be shifted elsewhere. You're the CTO and you ask the BOD for another $150k/y (fully burdened) + equity to hire a new developer with PDF skills.
The COB asks you directly: "You can get a battle-tested PDF parser off-the-shelf for little or no cost. We're not in the PDF parser business, and we know that building a robust PDF parser is an open-ended project, because real-world PDFs are so gross inside. Why are you asking for new money to build our own PDF parser? What's your economic argument?"
And the killer question comes next: "Why aren't you spending that $150k/y on building functionality that our customers need?" If don't give a convincing business justification, you're shoved out the door because, as a CTO, your job is building technology that satisfies the business objectives.
So CTO, what's your economic answer?