I've discovered an 11th Commandment (or so it seems):
Thou shalt not launch a new product or service without a Powerpoint deck.
I sit through—and click through—a lot of them. I learn a lot about founders, and technology, and markets, and branding, and launch strategies... and passion, of course!
But ask about customers—real people, not abstract "markets"—and the room gets quiet quickly.
Like the early explorers, companies just sort of make it up, filling in the gaps of what they don't know with what they think they know, and what they've heard. They even copy the work of others, just like many early cartographers.
The result is often a map like this one—from 1626—that depicts California as an enormous island with a smattering of sea monsters off its coast. (Perhaps John Speed was prescient?)
The only way to draw an accurate map of your customers is to go out and talk to them—even if that means crossing an uncharted frontier to get there.