1. The game got great reviews, so quality did not suffer.

2. In the 1980s, distribution of cracked titles was mostly by modem (BBS) or warez disks, and thus a LOT slower than today. Cracks would take weeks or months to get wide distribution.

3. Atari was paying me $30K/year. Let's double that for total employee load. It took me two weeks to write the copy protection, so that's roughly $2500 cost to Atari.

4. I think Atari's profit on carts was about $25. So to break even we had to deter 100 people from pirating the game and just buy it instead. You can wiggle the profit numbers around if you like, but it doesn't change them appreciably -- it's just not that many buyers that we have to swing in order to pay for development.

It's impossible to get numbers, but the fact that the game wasn't trivially copyable by the kid down the street (it took an expert cracker 3 days), that cracks were hard to obtain (little inter-pirate communication, bad distribution systems), and that the title sold maybe a million copies makes it almost certain that the protection not only paid for itself, but did so many times over.