A trend in Tarantino's movies seems to be that the bad characters almost always lose because they make idiotic decisions. Has he explained why this is so?
Reservoir Dogs: despite knowing that there's a rat amidst them, the entire gang still decides to stay at their meet-up place, which they should be able to deduce is known to the Police. Mr Pink even tells them that much, but Tarantino provides no reason for why they don't listen to him (or why Mr. Pink doesn't listen to himself).
Jackie Brown: Ordell trusts Jackie Brown with half a million dollars. Why in the world would he do that? He has trusted her before, but only to bring in small amounts (say, 10-50k dollars) at a time. There's no way a man like Ordell would trust a sneaky, clever, and desperate woman like Jackie to bring the entirety of his fortune in a single go. What makes it worse is, Ordell doesn't even need to do it. The police have currently nothing concrete on him. He can just kill Jackie, lay low for a while, and then bring his money in some time later, small amounts at a time.
The Hateful Eight: While Jon Ruth and OB are dying, why don't Joe Gage, Oswaldo Mubray, and Senor Bob, along with the fella in the basement, immediately strike? WTF are they waiting for? They only need to take out Marquis, as Chris Mannix does not have a gun.
Inglorious Basterds: Why would the Jew Hunter trust a well-known Nazi-hating mad-man like Aldo? Especially when he has no leverage? The only thing he had to offer was "to not make a phone call". Well, he can't make that phone call anymore, so his leverage is gone, so of course he should expect Aldo to utilize that against him.
Pulp Fiction: Vincent going to the f***king bathroom without his machine gun at the place of a person he is hunting.
Kill Bill: Bill had Beatrix sedated, and could've killed her easily. But nope, decides not to. Because giving a speech is more important than surviving I guess. Moron.