Nami’s attitude about continuing to chase money is indicative of how old habits die hard. While her obsession with stealing gold & treasure began as a method to free her hometown of Cocoyashi, she has spent almost half of her life, during her formative years no less, developing the skills and attitudes that make her a specialist in gaining wealth. Even though the village is safe, a significant part of her personality is still focused on acquiring material resources. In fact, her knowledge of what cold hard cash can do, and what people are willing to do for it, is a contributing factor to why her reaction to the $30,000,000 bounty is somber & fearful. Zoro has a similar reaction because as a retired pirate hunter, he knows the caliber of bounty hunters that will be chasing that $30,000,000.
Sanji & Usopp, on the other hand, are both very excited & happy to learn of this bounty, celebrating & laughing along with Luffy. These 3 characters have very much intentionally set out to become pirates and so they consider this to be an indicator of success, contrary to Nami & Zoro who ultimately have alternative goals and only see piracy as a means to an end.
We see an example of Luffy demonstrating that kindness can be revolutionary. The world government, when setting the bounty, discusses how Luffy has defeated multiple pirates with enormous bounties on their own heads, and so set Luffy’s even higher because he must be a worse threat than them to have defeated them. However, they never stop for a moment to consider that Luffy is defeating these powerfully evil pirates because he is a good guy, and so we see how authoritarian power cares not for actual positive results & helpful impacts on society but instead only cares to eliminate threats to its own power. Even still, we also see that Luffy is, currently, anyway, hardly a threat to the Marines, as he offers aid to lieutenant commander Fullbody and demonstrates compassion for the soldiers that almost blow themselves up with the faulty cannon.
Last note, we are shown more struggles with addiction, this time Shanks being hungover when Hawkeye finds him on his island, having sworn to stop drinking, and then immediately pulling out more alcohol to celebrate. Common signs of alcoholism are over-drinking, deciding to stop drinking entirely, and then failing to meet that goal and beginning to over-drink again. This cycle is a nefarious trap that affects millions of real people in all states of mental health, and seeing it accurately portrayed, even for comedic effect, is, in my opinion, beneficial to the audience, particularly a young audience forming their own first opinions on the nature of substance abuse.