Nothing much here to discuss, the Private key share was that of an airdrop wallet meaning the newbie must have been an airdrop hunter which I'm very positive they don't earn much to worry about their funds been stolen. In most cases this guys (Airdrops hunters) have numerous wallet for different campaign so some of the case you think are mistakes aren't.
On the other hand, ignorance is the cause of this problem, just like the user above me mentioned, if you consider the security of your coins as a priority, spending some time to get educated on how to safely store your sensitive wallet information should be your number priority. But instead most newbies aren't concerned about that which is why, they get punished by the scammers out there. The good news here is that, those experiences (lost of funds) comes with lesson and since experience they say, is the best teacher. It's quite ok they make this silly mistake now (involving less funds) and learn from then.