Challenging people to do stuff you won't reveal the nature of until they've committed to it--with no mention of incentives or alternatives--is not a "dare," it's just an inconceivably-shitty contract.

> Neither UX nor the Product Managers enlisted. Why not?

> Seven people joined, two dropped the day before, and when the challenge was revealed, one silently disappeared.

> Four brave souls to face the challenge…

All this shows is that out of his 13 devs, 4 of them will agree to anything.