How about this little theory:
A hacker has commited a grand bitcoin theft a while ago and is now trying to clear the trails to these Bitcoins through a puzzle. The one who will win the grand prize is the hacker himself, who can now hide behind the claim he has won the Bitcoins with his sheer knowledge.
Edit: Maybe the victims can ask for a subpoena to check a certain Binance account? Maybe there is another account at Polo, that might be interesting for LE.
A few addons to my theory:
(OP's wallet from 04-04-2018 until now)
https://www.blockchain.com/btc/address/3KCEGC4GaATQCnzogrpSDRJLKAjWvgudmW (OP's wallet from 04-04-2018 until now)
https://www.blockchain.com/btc/address/13hLyfRHg7p9Zw7WHToRT67JR1HR92Mvxw (OP's wallet until 04-04-2018)
Just quoting myself. Well played, OP.