[Tuor of Gondolin]

Here's a thought. I believe it's said that some of the houses of the dwarves were
at least partially "evil", or had trends so, and that some fought for Sauron in the War of the Last Alliance. What if those houses, abetted by their fear of
long-term diminishment and extinction in Middle-earth, sought to take over Kazad-dum and then, perhaps allied with ents gone bad and/or Easterlings, to
"revenge" "harms" done to dwarves by elves by taking the Grey Havens and Rivendell to prevent elves leaving safely Middle-earth. With a possible dwarf
civil war ensuing by the dwarves with good relations with hobbits and elves opposing them?