One Piece Chapter 568

[Archangel]

I dont know I feel it strange for Luffy to get such a large boost in bounty without becoming substantially stronger. He hasn't mastered any form of Haki yet nor introduced any new attacks forms really. Not that I doubt his head will raise several hundred beli after breaking out of Impel Down and assaulting HQ, but just saying.

Oda has already explained that Bounties aren't proportional to the pirate's strength but to how much trouble they cause for the world government

Now since his last one Luffy has defeated a shichibukai, punched a tenryuubito, fought an admiral and escaped, penetrated and escape from Impel Down along with hunderds of other inmates including some with bounties over 100 Mil, is now fighting along with the most wanted pirate in the world and had his connection with both Dragon and Ace exposed to the entire entire world

That's one hell of a shit list to ignore

[Carnage]

Oda has already explained that Bounties aren't proportional to the pirate's strength but to how much trouble they cause for the world government

I know that, hence why I said "Not that I doubt". My point was, it will be strange for him to have a bounty so much higher than so many pirates on and above his level. He will have to become stronger if he wants to compete with other 500-600 million bounties that could be as powerful as their bounties portray.

[Sentenal]

This arc also isn't over, and I would seriously doubt that this entire arc goes over without Luffy kicking at least someone important's ass.

[Assertn]

Another possibility is having someone join with a bounty of 299,999,950

[Archangel]

I know that, hence why I said "Not that I doubt". My point was, it will be strange for him to have a bounty so much higher than so many pirates on and above his level. He will have to become stronger if he wants to compete with other 500-600 million bounties that could be as powerful as their bounties portray.

Not any stranger than Chopper having a 50 belli bounty when he has single handedly beaten a CP9 member

And it's by fighting stronger enemies than himself that Luffy has evolved so far so i don't see what your problem is