It seems what ever design you contemplate employing a fee can always be gamed by an attacker so that he pays no cost.

The attacker can make his own DE and receive the fees. So then he attacks the other DEs (which are honest) 100% of the time but doesn't attack his own DE (or attacks he own less frequently) thus all users migrate to his DE. Thus he is losing much less in attack fees than he is gaining from fees.

Since more than one attacker can do this to each other, no one will use DE.

P.S. I knew that there would be a leak in fees that would maintain my conclusion that DE is fundamentally impossible. Sorry when I come to these sort of generative essence conclusions they stick.