The grow up Peter Pan had me in stitches.

I understand your point of view but I see no gross neglect here. If following the rules they deserve the spoils. After earning those spoils such earned spoils are theirs to do with what they please including cashing out. I say that as someone who has cashed out $0 and invested a handful of thousands into Hive. I thought something more sinister was going on. The little hamster in my head was doing wheelies. I don't even want to type out the scenarios I was coming up with. I was happy to see it was a powering down: cashing out grievance. Would it be wise to build a stake? Of course, it shows commitment to the chain. But only they know what is best for them. I find it hard to fault anyone for cashing out what they earned. I don't fault those who don't vote on such accounts either. That's the beauty of the the blockchain we each have our weight and use it as we see fit to do so. I would be more worried if it was large stake holders/ community leaders / witnesses doing so with large amounts of Hive but all I'm seeing displayed here is what I consider to be typical end-user behavior that will be much more frequent once WEB2 users flock to Hive.

What does Splinterland get?

Exposure is the answer. The art contest like the other contests is the reason why so many posts about Splinterlands are on the Blockchain and elsewhere. Possibly the use of the artwork to some degree? Likely also can be used to scout for the next artist they might hire to help create new cards (just a wild guess on my part). I do agree that some sort of rules should be put in place for the handing out of rare assets. To play devil's advocate here, the holding of packs might be their way of keeping something in their accounts to show support. There's many possibilities here.