Tougher than the toughies, smarter than the smarties, and sharper than the sharpies, Scrooge made his money fair and square. Part mysterious trillionaire, part adventurer, his wealth combined with his overwhelming confidence has bred an unpredictable nature and a belief that anything can happen and everything is possible if you're willing to work for it. His love of money isn't because he's greedy, it's because he knows how he earned each dollar; each coin is a memento of a past adventure.
Once an avid adventurer, Scrooge started to slow down and began spending more time back at home, until his nephews rekindled his desire for adventure. He values hard work and integrity and continues to be a hard worker in his old age. He also wishes to instill values of hard work and dedication to his grand-nephews, as seen in "The Great Dime Chase!".
Stern, yet kind-hearted, Scrooge takes great care in mapping out his paths, using the knowledge he has gained over the years to keep himself safe and out of harm's way. He is happy to impart his knowledge to others, provided that they are willing to listen.
Before Della's disappearance, Scrooge was shown to be a more jovial, fun-loving, and generous duck who relished in adventure and helped those in need whenever he could, but after her vanishing, he was shown to be much more bitter and rather jaded.
Like his nephew, Donald, Scrooge can also be quick-tempered, (but he does not have a temper as strong as his nephew) especially where his pilot, Launchpad is concerned. His rival, Flintheart Glomgold also brings out his temper, though in a different way. Scrooge is determined not to let Flintheart ever take his position of richest duck in the world.
Scrooge is shown to have an obsessive side, such as when he wanted to stop at nothing to climb Mount Neverrest, even putting the children's lives at risk to further his goal. Nevertheless, he will ultimately put the safety of others above his selfish desires. Indeed, his greatest shame is his failure to save his niece, Della, from her ill-fated space voyage.
Scrooge is also very self-righteous; carrying great pride in the experience and capabilities that made him the legend he is today. He often states who he is to assert dominance or going into a challenge knowing he will achieve, this shows he has put himself on a mantle. However, he also feels that it's only right to share the stories and experiences of his past with his family, as just like what Djinn had explained to him, it can be used as the start of great legends to come for his family's descendants.
Immortality: Scrooge is known for his long lifespan. By his own account, he was alive during the Gold Rush of the 1800's. His long lifespan is the result of encounters with life extending Supernatural forces, like spending time in timeless demon dimensions or being cryogenically frozen while spelunking for treasure. Twice in a row. Druid stones from Castle McDuck granted Scrooge immortality since his sister Maltida is still immortal even when she leaves the castle. Webby confirmed Scrooge's immortality in How Santa Stole Christmas!.
Skilled hand-to-hand combatant: Scrooge is a very strong duck physically, and is a master combatant. With his raw strength, he was able to defeat a Rock Giant. His strength and endurance makes him the only person able to dive and swim in gold coins (a skill later learned by his grand-nephew, Louie Duck). He also can weight-lift money bags that makes him strong.
Genius-level intellect: Self-described as being "smarter than the smarties", Scrooge has proven himself to be extremely intelligent on numerous occasions, from his business sense to his knowledge over ancient history.
Multilingualism: Scrooge has proven himself to be an adequate translator, able to read ancient languages such as Atlantean and the unknown language of Montemplumage's City.
Scrooge has many useful talents and skills, such as farming, treasure hunting, and prospecting.