If you are the first person to write a bot to automatically submit entries, you could submit most/all of the allowed 10 million entries.

OK, maybe your IP would get banned, but what if you have access to a botnet and, therefore, lots of IP addresses?

OK, maybe they have a captcha, but what if you trick your botnet victims into filling in the captchas during their normal web browsing sessions, by pretending to be a google bot-detection page?

OK, so you win, but the address is a random address that isn't yours. How much would you have to give the person whose address it really is, to pretend you live there? Half? Still not bad.