An interesting comparison. [Not one he'd personally make.] We don't have many tales about those that decided not to go to the Blessed Realm as my people did. Not more than they must have led a miserable existence under the dominion of the Enemy. [And some turned into orcs in his service but that's the theory Fëanor personally detests so his not willing to share it.]

There were no curses involved though. [To the extent of his knowledge. Still, there might have been and he wouldn't even know. All that exodus story always sounded suspicious to him.] And my people built cities underground. [A city. Singular.]

Now that's exactly something servants of the Enemy would say, and by Enemy I mean Melkor or Morgoth. Though I doubt he'd use any of those names. [Especially the second one.]