I understand it's rare, but I just got 3 starred by a TH8 using Balloonions (I am a TH7) and they took 224k of each resource, and I was only sitting at 50% storage capacity when they hit me (2 mil of each resource).
They are out there, and it really doesn't take that many resources for a TH7 to show 400k+ combined loot to a TH8.

