If the island was not in the air, then BM, even without Haki, would have defeated them after their last attacks. What is the sum of 4 by 2?
Luffy promised to defeat BM and Kaido. BM can still get up and go to Kaido. Don't forget, BM was declared the loser just like Luffy was 2 chapters ago...
Luffy 6 billion and that's it.
Luffis bounty for Kaido will be Luffy's last bounty because after this arc, there will be a final war with the Government. And there will be no one else to give Luffy's bounty, and his bounty at the end of the manga should be higher than Roger's. It's 6 billion...
Luffy's reward after Wano - 6 billion
Zoro's reward after Wano 1.5-2.5 billion
Sanji's reward after Wano 1.5-2.5 billion
Law's reward after Wano less than 1.5 billion
Kid's reward after Wano less than 1.5 billion
Killer's reward after Wano less than 800 million
And so, if BM lost to these 2, then what kind of reward will the Government give them? More than Zoro or less?
Imagine if their bounty was greater than Zoro's!
While Zoro one-shots each of them.