Creation costs like the cost of an advanced degree?

No, copyright has little to do with advanced degrees. The creation costs are the time and resources needed to produce the book, movie, software project, or other work, which can be substantial.

There's a better argument for patents, but still weak.

That was a rhetorical question

Right, and rhetorical questions by definition don't have good answers. There needs to be a reasonable limit here, and what's reasonable depends on what specifically we're talking about.

For example, I benefitted a lot from my public education, but I can't really quantify the impact to a a dollar amount, so I don't think it's reasonable to say my career success is due to public funding.

For me to accept that an innovation came from the public sector, I'd need to see a direct link between public funding and the innovation. Just saying a company got a tax incentive to put an office somewhere doesn't mean all innovations from that office is government funded.

Is it unreasonable to say that the state is paying you to drive?

Yes, that's unreasonable.

Driving is heavily subsidized by the state. For example, a lot of the funding for roads comes from income taxes instead of direct use taxes like registration and gas taxes. Even so, I don't consider that to be paying me to drive, but it is an incentive to drive.

The government does pay me to have babies since I get a tax credit if I have kids. The difference is I have to do something proactive to get the benefit, whereas the roads will be funded whether I drive or not.

If a company gets a tax incentive to put an office somewhere, that doesn't mean all inventions made there are publicly funded unless that's specifically called out in the incentive deal.