I've attended the funerals of my enemies just to pay my respects for the rivalry that we had.
What? You have enemies? Like the Joker and Batman or Lex Luthor and Superman?
Honestly, to me, that word describes a kind of relation that mainly exists in comic books and between nation states.
I don't actively search for their obits or anything, but if I learned about a funeral, I'd make the time to visit, stand quietly, and reflect.
Probably not the healthiest thing, but not my unhealthiest quality either. At the moment it is only theoretical. But I can think of 3 or 4 I'm now likely to google up and see what they're up to and assess who is closer to the pine box. :)
Do you have grudge against those people, such that put effort into trying to undermine or defeat them? I feel the word "enemy" has connotations of a kind of direct, sustained opposition that just seems like it'd be really unusual (and unhealthy) in real life.