And Feanor most of all. I mean, that guy was badass personified. He had such strength of wil that when he was born, the burning power of his spirits killed his mother. In the lands of the Immortals. Where the Powers of Life, Love, and Healing are just down the road.
With pretty much no martial training whatsoever, he developed his own weapons technology. With no more than revenge on his mind and a rarely-excercised title, he got his men ready to sail, stole ships and whacked some of his fellows who owned them, learned to sail, and then went off to mash Morgoth’s face.
Bloody Morgoth!
And then, Morgoth was so scared of his he sent a whole damn flight of Balrog’s to paste him (and only Feanor). And the Balrog’s ran off like scared little girls when his sons showed up!
For any non-geeks here, this is the guy who made magic gems so powerful they could have remade the original, much more awesome, sun and moon. These gems had the power to alter reality, such that the Powers themselves were allowed to fix things just by having one. Beren was able to come back from the dead (which humans are never, ever allowed to do) principally because he had held one. In his severed hand.
Feanor was so badasss that he when he finally died (to the aforementioned flight of Balrogs), the Valar said “Huh… we’d better not give this guy another body or he’ll start wreckin shit up.” He is presumed spends his time being very put out and trashing the God of Death in chess.
In retrospect, too, his attitudes are a little more understandable. Seriously, would you respect the Valar if Morgoth was able to basically waltz into their home, feed the (original, more badass) sun and moon to his pet mega-spider-demon, and waltz out again? And the Valar’s plan was “Hey, Feanor, hand over the gems.” And upon finding out that Morgoth had further killed your dad and stole the Silmarils, they aid, “Ho hum, well, don’t go after him.”
Things would have been much better if they’d just told Feanor that it was very unwise, but that the choice was his to go or stay, but having gone he could not easily return. But the Valar, though wise, are fallible.