People that think it's gonna be 800 million for the top F6 are desensitized in regards to bounties, too caught up in the "find Yamato and fight a commander for their position" subplot, and thinking about Perospero too much. As you stated, basically all the New World captains that aren't Worst Generation members are under 400 million (except Oars Jr but his ancestor/race has some hype so whatever). And even then only Luffy, Law, and Kid are above that number in the WorGen that we know of. I find it strange that Who's Who or Sasaki would have nigh-commander level bounties. Commanders are the strongest and most trusted underlings in a Yonkou's crew. That status alone should bump your bounty a lot. Then when you look at every known bounty above 500 million almost all of them are either commanders or Yonkou. Enter Chadspero. He does give a flicker of hope for all the F6 simps out there, but he's also arguably the biggest outlier in the 500 million and up range.