During the Orange Town arc of One Piece viewers were treated to a fun and unique origin story for the main antagonist. While this isn’t super unique to anime as a whole it is fairly unusual for these earlier episodes of One Piece. Normally flashbacks involving antagonists are limited to how they directly affected one of the Straw Hats, as with Arlong flashing back to his treatment of Nami. Instead with Buggy the Clown audiences got to see exactly what turned Buggy into the pirate he is today, and perhaps a little bit of why his personality is what it is today as well.
One Piece follows the story of Monkey D. Luffy as he gathers a crew and sets out for the Grand Line in an effort to become King of the Pirates. In his effort to gather a reliable crew he meets with more than a few notorious pirates who mostly stand in his way, with one major exception in the form of Shanks.
What Happened to Buggy?
When Buggy was just a pirate in training he was on a ship with Red-Haired Shanks, and due to how they spent their time together he holds a special place of hatred in his heart for the other pirate. During a raid Buggy finds a treasure map that he believes points to a location in the middle of the ocean. Given his intense love of treasure and wealth, he immediately hides the map from his shipmates and makes plans to go seek that treasure on his own.
Shanks talks to Buggy about another valuable item captured in the raid, a Chop Chop Devil Fruit. This item he says is worth a fortune in berries. Of course, Buggy must have that as well so he stages a showing where he eats a fake version of the fruit while actually stealing the real one. The crew is fooled and believe that the fruit they captured was fake all along.
Later when Buggy is trying to sneak off the ship Shanks catches him and engages in casual conversation. During this interaction Buggy accidentally swallows the real Devil Fruit and in the process loses his ability to swim. He then falls overboard and must be saved by Shanks. However, Buggy does not view this as a benevolent act. Instead, he blamed Shanks not only for the loss of the valuable fruit but also for his inability to ever swim down to his sunken treasure.
Obviously a Mistake, But Was It for the Better?
Buggy believes that his mistake of swallowing the fruit cost him all of his dreams. In his own words, he had to instead focus on collecting all of the treasure on dry land. That aside he also laments his inability to sell the Devil Fruit, but he became functionally invincible in trade. Given what he lost and what he gained it is hard to truly say that he didn’t come out better in the end.
While there is probably a fair amount of treasure sunk into the sea during this great pirate age in One Piece, unless you have maps to it, it's highly unlikely that you would be able to find any of it. With that in mind, he really is only missing out on one single cache. Additionally just because he can’t swim doesn’t mean he can’t have lackeys do it for him. During the fight with Luffy, he demonstrated an obvious willingness to delegate as with Cabaji. Realistically he could have sailed his ship to that location and forced one of his sailors who hasn’t eaten a Devil Fruit to swim down and retrieve it.
In regard to the Devil Fruit, he did lose out on the profits that he would have made on selling the fruit. However, as mentioned prior he is functionally invincible. His fight with Luffy indicated that he has certainly practiced the skill well enough to imply that he uses it frequently. Surely the more dangerous heists that he has been able to pull off using this ability have more than paid for what he would have gotten for the fruit. His notoriety and bounty alone certainly suggest that he has been fairly successful at being a pirate.
While Buggy certainly regrets eating the Devil Fruit, and holds intense resentment against the man who he believes forced him to. He only proves that he has an extremely short-sighted nature, he is unable to see all of the benefits that eating the fruit has given him. His rage has also prevented him from out-of-the-box thinking which would still have allowed him to accomplish his dreams despite his new disability. Buggy should in fact be thanking Shanks. Not only for having saved his life but also for having caused him to eat the fruit that allowed him to be so successful in his chosen profession.