Last week I was invited to speak at a TEDx event, and today I turned that offer down. It’s not that I don’t like TED — I think the organisers have done a great service to popularise thought-provoking ideas in an easily-digestible format. And the subject of the TEDx event, centring on science and society, is definitely close to my heart. But the problem I discovered is this: TED doesn’t pay its speakers. (...) None of the speakers — at TED or its little sister TEDx — get paid. This is despite the fact that tickets to a full-scale TED event cost something in the realms of $6,000.