As someone involved in a very local run this weekend, people aren't that dumb. They know that there will be a company making sure the run actually works, and a

As someone involved in a very local run this weekend, people aren't that dumb. They know that there will be a company making sure the run actually works, and a small portion of proceeds goes to the charity. Actually, it really depends on the number of runners, so after a hundred or so runners, the amount to charity increases per additional runner. It's a bit like saying that people play the lottery and think it is an effective way to support education in their state. No they don't. They know most of the money doesn't support education, but even if a small amount does, the other benefit (playing the lottery or running a 5k) is still worth something to them.