Why does that sound so much like a kid saying "That didn't hurt" while furiously rubbing the punched arm?

Apple cared enough to try and appeal the case to the highest possible level (SCOTUS). To paraphrase a commenter on Ars Technica: $500,000,000 is a lot of iPads/MacBooks sold. All down the drain due to anti-consumer shenanigans.

Apple would appeal a $1,000,000 court case until and unless they expected to lose more money by fighting it than by just paying the fine. And essentially, $500mil is more than enough money for keeping on some lawyers for half a decade.

Still, it's worth comparing to how much money they make. So, a half-billion fine once in the last few years, and they made $18billion this quarter:

http://moneymorning.com/2016/01/26/q1-apple-earnings-2016/

I honestly don't see Apple being seriously hurt by this.

Apple partisans act as if the money is coming from Apple's petty-cash drawer. My point is somewhat similar to your: in that they would do anything not to pay the half a million dollars.

Comparing to the numbers in their last FY (Oct '15), the settlement is 0.94% of their annual profit. I too wouldn't be "hurt" by a 1% fine of my net annual income, but I'd rather put it to better use.

Relative to what they actually made off of ebooks? Unlikely although I don't have numbers offhand.

Relative to the company as a whole. Stuff like this is built in to the slush fund as "hazard" money. The shareholders could care less. Apple has more money than the African continent. I doubt anyone is overly worried.