Nothing is Guaranteed With AdSense
As frustrating as it is to get disabled from AdSense, keep in mind, Google never promises us anything and they will do what they can to protect their own revenue.
If that means disabling accounts they feel are at risk of producing click fraud, they will do it.
I know that's a tough pill to swallow and I can imagine it does feel horrible to get your account disabled, but when we all "accepted" the terms and conditions upon signing up, that is basically what we were agreeing to.
There are no guarantees with AdSense and we are all at risk of losing our accounts.
Now I do believe that the system has kinks, and I believe some innocent people are disabled, but that's why you cannot put all your income eggs in one basket. Google has to protect their advertiser's money.
No one is safe from getting banned... not even me... and it's just one of those things that comes with the territory if you decide to join the AdSense program.
Google will always safeguard their advertisers because they are their customers -- not us. And if they feel their money is being wasted on fraudulent clicks (even if it's only potential), they won't stand for it.
Back in 2012, Google began disabling a lot of accounts. I know because I got tons of emails of frustrated people. It was kind of odd how it all seemed to happen at once.
AdSense is great, but it doesn't provide stable income or security likeaffiliate marketing or selling your own products.