Luffy is selfish af!! Dude was ready to go in wci despite sanji's letter and let nami in trouble against enraged army because of what ?
Now because and thanks to him, they are facing two yonkou at the same time lmao! Wonder what people would have said if luffy and others were real...
Sanji is not selfish but worse ...
Sanji would be dead if Luffy didn't go there. He wanted to go alone, it was the others that asked him to let them come.
If Luffy didn't take that decision they wouldn't go to Wano but start a war with Big Mom instead to avenge Sanji.
Nami can take care of herself. She can act scared sometimes but she's actually really brave.
So this is not a good example of Luffy being selfish, it's just him caring about his nakamas, the opposite of being selfish.
Luffy is whimsical and carefree, not really selfish.