Someone else linked to that somewhere in the comments. The idea is that if you tell all your friends about your high-status plan to write a novel, and they congratulate you, then it becomes a 'social reality'...you get some of the benefits of having written a novel without having done any work, and so you're less likely to do the work.

I wonder what would happen if you told your friends about your plans and they were extremely skeptical. From personal experience, I think that to a degree you feel more motivated to 'show them' and 'prove yourself', as I did when nearly all my friends and family were skeptical that I could learn to sing. I did learn to sing. However, my friends and family were also skeptical that I could become the youngest person to swim across Lake Ontario (at 14) and I didn't end up doing it...without my parents' material and financial support, it was pretty much impossible.