Yes, they have the data that shows a few whales will make those transactions worth it, at the same time they are counting on catching the occasional non-whale slacking. Trick enough minnows into a net and you have the same mass as a whale.

You're actually thinking much more intelligently than they do. I was in games for almost two decades, left a couple years ago. The vast, vast, vast, vast majority of money made is from whales, it's not even close. I've worked on games where we had to speak to banks in both Canada and the UAE to allow a man to make six figure purchases per week. He and one other whale were over 75% of our revenue.

Now the intelligent thing to do to make money here would be, as you said, getting minnows to spend -- but that takes too long and the people who run these things want it now.

So rather than selling each armour colour or whatever for 50 cents each, they'll charge 20 bucks for all of it, pricing out 90% of users*, and barely making money on it, instead of a million people buying it making them a tonne of money. (*this is a personal experience tale, this did happen, these numbers are unaltered.)