I have one question for everyone who ever sat through a marketing course.

What was your professor's cost per acquisition?

You don't know. Neither do they. Nobody in that building ever had to know.

Here's why. Business school marketing is taught from case studies: Coke, Nike, Apple. Fortune 500 companies with famous brands and massive budgets. When a brand that size runs an ad, nobody can trace a single sale back to it.

And nobody has to. The brand does the selling. The ad takes the credit.

Now remove the brand. Remove the budget.

What's left is the actual job: making a stranger pull out a card and buy. No reputation to lean on. No billboard doing the warm-up.

That job has a scoreboard. Traffic. Conversions. Split tests. Either strangers bought or they didn't, and the numbers don't care how elegant the theory was.

I never took a marketing class. Carnegie Mellon, engineering. Everything I know about making strangers buy, I learned by paying for my own traffic and watching split tests kill my favorite ideas.

Since 1998 that education has produced over $100 million for my clients. $203,000 in 45 minutes. No agency. Ever.

The difference between me and the professor isn't talent.

It's that I was never allowed to be wrong for free.

There's a name for expertise that never faces a scoreboard: unaccountable. Business school runs on it.

Your business can't.