Those figures fit with what I remember about ad revenue. If I remember right, it's normal for around 2% of hits to convert into an ad click. If we pair that with a $0.50 mean earning-per-click (memory and a cursory search of the Internet say this is reasonable), we get:

  $0.50 * (1.5 million * 2%) = $15,000/mo.

That leaves some leeway for Crranky to have worse performance and still hit his quoted $10,000/mo.

$0.50 per click and 50 impressions per click implies $10 CPM... Isn't that a bit high?

It's achievable today, and was even more easily achievable 5 years ago.

It's possible - see my post towards the bottom of the page.