I'm 30% through writing a 10-20K word blog series about something that I've been working on for the last 6-8 years. I've probably written ~5K words already on blogs unrelated to my series where I'm kicking around the ideas that went into my project. Finally, the project probably isn't that interesting unless you've encountered a very specific type of problem before. Which means I probably should put in another 5-10K words to market it.
Sometimes it's not about confidence. Sometimes it's about complex social dynamics and how people react to suddenly being thrown into the deep end of a domain that's completely new to them.
"Tell me about a technical challenge that won't make me feel inadequate or be difficult to follow. Don't make it too simple though because then I'll think you're an idiot."
Ah yes, just be confident. That's the ticket.