Can you earn from Adwords?

I read the last moments an e-book (I won’t tell its’ name), that tell that the blogger or the internet entrepreneur had made about 5,000$ from Adsense for spending only 1,200$ on Adwords.
I don’t know he think people are stupid or just attract traffic.
What make me says that he lies?
He said that he get traffic from Adwords and then get earning from Adsense.
But he forgets that he pay for each click on Adwords and in AdSense he need many visitors to get a click. So even if the click value is higher in his site than he pays for Google Adsense he’s earning we’ll be less.
Let’s take an example:
You put 0.05 per click in Adwords and you spend 1,500$
You’ll get 30,000 visitors with Adwords
Now suppose that you get 0.15$ per click in your web site with Adsense.
Not 30,000 visitors will click but only 8% in the better case!
So you’ll have only 2,400 clicks and then 360$ of earnings!
Please don’t believe on those e-book, try to think well before making any decision.
Good luck with Adsense and blogging.