This. When it comes to money, people will exploit it as much as possible.

From their FAQ: "Do I have to pick the winner of my contest? If your contest receives less than 5 entries by the time it ends, you're not obligated to pick a winner. You have the option to extend the contest for seven (7) days for free. 'Extend Contest' and 'Contact us' link information is available on the contest page.

So, what if I just forget to log back in and award people the prize? Does google automatically pick a winner?