In The Book of Life, at least three of the deceased Sanchezes died by trying some stunts as bullfighters, all believing that "(Insert subject here) are for cowards":
Luis tried fighting three bulls at once because "fighting just one bull is for cowards".
Jorge tried fighting a bull with just one arm and leg because "fighting with two arms and legs is for cowards".
Carmelo fought a bull without using a cape, because "using a cape is for cowards".
In Grave of the Fireflies, the main character, Seita, endures incredible hardships with his sister during and after WWII. Most of that hardship is a result of him running out on his kinda-mean-but-not-that-bad aunt's house to live in a cave. One of the reasons the aunt resents him is that instead of working, he goofed off during the day. And instead of getting a job, he runs off with his toddler sister. Even when things become so bad that their lives are threatened, instead of simply asking his aunt to take them back, he sticks it out, while his sister eats mudballs out of hunger. And then both he and his sister die.
This is a rare justified example, though, because Grave of the Fireflies was originally a novel, and the novel was written by a WWII survivor named Nosaka. Seita is an Author Avatar of Nosaka, and Nosaka was torn up with guilt that in real life, he believes he really did indirectly cause his sister to die of malnutrition.
In addition, the authorial intention from both the director of the film and writer of the novel meant for Seita to be viewed as a spoiled teen. In several interviews, both said that Seita is a prideful teen who could not endure minor blows to his ego that many others of his generation would have endured (they jabbed at the teens of the '80s in the same interview, saying Seita acted like youths of the current day), and turned against rest of the world which resulted in tragedy. In another interview, the director went as far as to say that the widowed aunt's words were not particularly cruel considering the situation and Seita killed his sister trying to to achieve an impossible fantasynote Interview in Animage May 1988 edition. It can even be argued that Seita was bit of a spoiled Upper-Class Twit who refused to study or work even as his cousins did, as Seita's father was a high ranking naval officer who commanded a war ship, and the relative wealth Seita grew up in can be glimpsed in the family's luxury goods such as the piano.
Olaf, whose fondest wish is to experience summer, even though he's a snowman. Unlike Anna, however, Olaf has the excuse of basically being a child and genuinely not knowing better.
During the reprise of "For the First Time in Forever," Anna is oblivious to the increasingly violent snowstorm surrounding Elsa. The result is a near-fatal ice blast to the heart.
The Hunchback of Notre Dame: While Frollo is a cunning man, he acts on this trope near the end of the film when he climbs on top of the gargoyle to kill Esmerelda. Considering that he is standing up straight on the over-hanging gargoyle, with no support whatsoever, means his body weight causes the aging statue to crack.
The dodos seen in Ice Age qualify: when the protagonists first encounter them, they're at regiment strength. After one rhubarb with the pathetic sloth Sid, they manage to topple off a precipice. Every last one.
The Jungle Book: Mowgli, especially during his second encounter with Kaa, where knowing that Kaa wants to eat him, still thinks that Kaa wants to help him, and looks into his eyes long enough to be hypnotized. If Sherk Khan hadn't shown up, Mowgli would have been dead.
Heihei in Moana is comically stupid. His Establishing Character Moment is him trying to eat a rock bigger than his head. After spitting it back up, he then immediately tries to eat the same rock again. Heihei is shown doing all sorts of stupid things throughout the film, such as constantly walking off the boat (in the middle of the ocean) or when food is put down in front of him he pecks the ground everywhere except where the food is. This is entirely Played for Laughs - as Heihei is also too dumb to die.
Pinocchio from Pinocchio (1992) is warned by the Cricket not to go to Dunceland, because his wanting of a life of just fun has caused him many problems in the past. However, Pinocchio goes there and pays it dearly. He almost ends being drowned in the sea as a donkey.
Gene and the other Nicelanders from Wreck-It Ralph have their town in danger of being destroyed, thanks to the eponymous Villain Protagonist, who makes the plot in their world work, leaving them. To clarify, Ralph is a Punch-Clock Villain, playing the bad guy in Fix-It Felix, Jr., with the Nicelanders as the NPCs. However, Ralph and Felix are the only ones who even seem aware of the fact that Ralph is the most important asset of the game. Without him, the game literally won't function, which will cause the game to be decommissioned, which will make every resident either dead or homeless. Instead of respecting this, or even trying to be personable to Ralph, the JerkassNicelanders shun him and are generally mean to him, which eventually leads to Ralph leaving the game to try to prove that he can be a good guy. Not only does this mean that Ralph isn't in the game (which, again, is vitally important), but by the time he comes back the game is only a few hours away from being unplugged, and it's too late for his return to make any difference because in the meantime Felix has vanished into Sugar Rush while trying to find Ralph to bring him back.
Bing Bong, Riley's imaginary friend in Inside Out, misreads a sign above Abstract Thought that reads "DANGER" as "shortcut", despite Sadness warning him that they shouldn't go in there to get to the Train of Thought and should go around the other way. They go in anyways and change into abstract versions of themselves that fall apart. They nearly get stuck in the chamber and get killed until Sadness tells them to fall on their faces to escape. Thanks to this, they wind up missing the train.
Trolls: Quite honestly, most of the Trolls qualify — after escaping from the Bergens in the opening prologue, they establish a new home in the forest, but don't bother with ANY defenses or warnings against any possible future discovery by the Bergens. Similarly, Branch tells Princess Poppy that her loud singing and boisterous party celebrations might attract the Bergens, but she blithely dismisses his warnings with terrible consequences.