Wtf is wrong with the NPCs? Got to 5k trophies a week ago and they pulled a fucking houdini.
They don't disappear, but they are limited to a very narrow window, and onlyfor a few days after each refresh. Stockpile when you can, or keep your defences low so other players will raid you and knock you back to the <5000 golden zone. One ship fleets are a good indication to those of us >5000 that you want to be hit. One player used his blocks to write "Hit Me", which was too tempting to resist. The real problem is that all blocks need to be destroyed to declare victory. If they were neutral, I.e. only to block attackers but not requiring total destruction, it would transform PVP imho.