I run one. When I've done cursory searches on our whales, I find people who appear (at least from LinkedIn/Facebook) to have great jobs. I don't get the impression the large guys can't afford it, generally speaking. I am sure it happens.
Good article that got passed around in my office on Friday. People who are 'gamers' and by extension people who make games tend to look at "whales" as gullible stupid people but a lot of us tend to exhibit the same behaviour about other things all while congratulating ourselves for not pay 5 bucks to support a game we've played for 50 hours.
That said I think there is a really really fine line you have to walk to keep your IAPs "ethical" and it's very temping (and profitable) to fall on the Candy Crush side of things.
If someone spent $30,000 on my digital cards, I'd look him up so that I could sleep at night and not worry that his kids are going hungry because of this.
(I'm not someone who sells these kinds of things, so I'm fully aware this is largely armchair quarterbacking.)
Creepy. I can't understand why anyone on HN thinks it's acceptable.
Using that information for other reasons without informing me is a clear, unambiguous, invasion of my privacy. It's probably not legal in the UK.
Tl:dr yes, it's creepy. Especially in the context of a game dev.