Lots of people on the internet are complaining that they earned nearly 100 dollars through Google's AdSense, only to have their account terminated at the last minute.
The usual cause given for the termination is "Invalid Clicks," although other reasons include a restricted placement of the Adsense code, modifying code, or putting Adsense on websites with inappropriate content.
Lots of people cry foul about their accounts being terminated, but the bottom line is that Google doesn't need to scam anybody out of 100 bucks; they're already rich, and they value their good reputation over a few bucks from one Adsense publisher.
One good tip to keep your Adsense account from being terminated is to be completely honest in your dealings with Google. If you accidentally click on your own advertisement, report it to Google. Tell them what happened and assure them you'll do your best not to let it happen again.
Google really isn't out to scam you.
If you do your best to operate with Adsense on fair terms, you can maximize your Adsense revenue without losing your account.