That being said, I would actually love to see an actual articulation of the points motivating this "response" rather than a page that can simply (and quite likely will) be perceived as arrogant.
a) Building a portfolio: xyz sites use my designs therefore i rule.
b) Building relationships: xyz site uses my designs therefore i rule, which is why next time they need a design they will call me.
c) Show off: xyz site uses my designs therefore i rule and i will post it on my site, which is why people will see what I do any anytime people want a design i will be a known name and have a portfolio to show for it.
He'd do it for free, but nobody will take him seriously.
Now.
Where was I, oh yes, I will accept this 50 grand challenge. Submit proof that you are worth at least 10 grand.