Oh great, now Negative Nancy found this thread too.
First, no-one is forcing you to donate. If you're so poor that 15$ is making you panic, don't worry! YOU DON'T HAVE TO DONATE.
Second, they don't charge the money unless the project receives proper funding, which in this case is a moot point since it only took 8 hours to reach that limit..
Third, this is a site for people who are interested in trying to help their favourite game developers make the games they want. If you're not interested, move on. It's not for you.
Easy, isn't it?