Naruto's Sasuke Uchiha described himself as an avenger. He was traumatized at a young age thanks to his older brother, Itachi, massacring his entire clan and leaving him orphaned and alone. His only goal after that was revenge. That is exactly what he set out to do when he joined Orochimaru to gain power. However, he was also embarking on a path of darkness.
Naruto Uzumaki never gave up on Sasuke and he spent years trying to get through to Sasuke and bring him back to the Hidden Leaf Village. In the end, Sasuke was forced to face his wrongdoings and crimes. While he returned to the village and the side of good, he can never fully distance himself from his former flaws and bad deeds.
10 Sasuke Is Arrogant
Sasuke Uchiha was notorious for being arrogant, and to a point, he had reason to be. He was top of his class, he had a good balance of strategic thinking, inherent power, and intelligence. However, he often took his confidence too far. He talked down to others, he saw himself as superior, and he was not afraid to let people know it.
After he left the Hidden Leaf Village, this attitude only got worse. Up until the very end of Naruto, he thought he was better than and more powerful than Naruto Uzumaki.
9 Sasuke Cares More About Himself Than Others
Sasuke only had one goal and it was somewhat selfish. Though it could be argued that Sasuke wanted revenge on his brother for the whole Uchiha clan, Sasuke was incredibly fixated on this to the point that he would be violent to anyone and everyone in his way — even if they were his allies.
Sasuke cared so much about his goal and how it would make him feel that he antagonized Naruto, Sakura Haruno, Karin, and many others. He felt that his acts of violence were the only way to get revenge.
8 Sasuke Would Do Anything For Power
Because Sasuke was so obsessed with power, he was willing to do anything it took to get that power. He hurt his friends (almost killing them at points), he turned against his village, he killed other loved ones, he joined Orochimaru, and he relied on the fuel of hatred. On top of that, he seemed so power-hungry that he could never stop, even before he left the village.
Sasuke was willing to overuse his chakra and put his life in danger. He was willing to bite off more than he could chew when he fought with Gaara — he didn't care if the curse mark would take over in the process.
7 Sasuke Would Kill His Friends
Sasuke was so obsessed with revenge that he was completely willing to kill his friends, making him no different from those that would kill their clans as Itachi did. However, Sasuke was largely unsuccessful at this endeavor. Though he and Naruto had many fights throughout the series, Naruto never succumbed to Sasuke's power completely.
Sasuke was even willing to try and kill Sakura, his teammate, the woman who loved him, and the person he would later marry, despite her also never giving upon him.
6 Sasuke Is Obsessed With Revenge
The obsession with revenge that characterizes a large majority of Sasuke's sometimes one-dimensional-feeling personality is a quality that fans didn't like. He had a one-track mind for violence, death, and self-satisfaction, despite what he said about his intentions.
Being so intent on killing for revenge makes sense because of how severely traumatized Sasuke was at such a young age, but it is a character trait that makes him a villain.
5 Sasuke Is Impulsive When Enraged
While Sasuke was generally a good strategist and could think of great combat maneuvers quickly on his feet, he also tended to let his rage get in the way of that. Sasuke would jump into a fight he usually would never have taken head-on due to the gaps in power level when he was mad enough.
This was exactly what happened with Sasuke's first confrontation with Itachi. Sasuke was nearly killed by his older brother who possessed more power than Sasuke could have ever hoped at his age.
4 Sasuke Doesn't Take Care Of Himself & Doesn't Heed Consequences Of Overusing Chakra
Sasuke was reckless — especially in a fight. He had beef with Gaara during the Chunin Exams, though Gaara had not done much directly to Sasuke. The two just wanted to test their abilities on one another. However, both characters took this to extremes. Gaara tried to fight him early and turned into the Shukaku while fighting Sasuke later.
Meanwhile, Sasuke overused his Chidori jutsu to the point of putting his life in danger and he did not pay heed to the curse mark, which spread across his body because of his chakra overuse.
3 Sasuke Is Rude & Insensitive
Sasuke has been known to say offhanded things — especially to Naruto, who is likely the only person who could have ever hoped to understand Sasuke, as they both lost their families and were orphaned at a young age.
Sasuke was certain that Naruto could never know how he felt because Naruto had never known his family. However, the whole village ostracized Naruto all his life, but did not extend the same coldness to Sasuke.
2 Sasuke Underestimates His Allies
Going hand-in-hand with thinking Sasuke was better than everyone else was Sasuke's constant underestimating of his friends and allies. He barely paid any heed to Karin and the others; he was constantly looking down on Sakura and Naruto, even after they confronted him with new and impressive power.
Sakura's incredible strength did not even phase Sasuke when they first met after a long separation period. Plus, Sasuke even underestimated the Nine-Tails which lived within Naruto.
1 Sasuke Tries To Do Everything Alone
Sasuke never had to do any of the things he did on his own, but even when in part of a chosen group, he was dead set on being the solo avenger. Sakura even pledged to throw her life away and help him get revenge, but Sasuke said no. He denied Naruto as well as the new allies he met within Orochimaru's ranks. He even planned to stab Orochimaru, who he was using to gain power, in the back.
Fans weren't upset that Sasuke was not loyal to Orochimaru, though. It was just sad to keep watching Sasuke make the same mistakes over and over until the final confrontation with Naruto.