There's a lot of people who don't learn anything from history because they just assume everyone in the past was stupid/evil, and then when they're faced with similar problems they make similar choices based on similar reasoning, thinking the situation is completely different. Because past people's concerns about what might happen were stupid because we know that didn't happen, but my concerns about what might happen are totally valid. And then add in that current events tend to have much more active propaganda surrounding them.

Like, it's very easy to look back at Vietnam and see it as the war of aggression that it was, but people would turn around and look at Afghanistan and say, "We're just defending their government and trying to build democracy," when Vietnam also had a puppet government to "defend." Anyone who opposed leaving Afghanistan would have opposed leaving Vietnam for the exact same reasons. But, because they don't understand why people supported the Vietnam War, they can't recognize the same line of reasoning in their own thoughts.

Really understanding history means understanding why people thought the way they did, and being removed from their cultures and conditions, you have to "steelman" their positions to understand the deeper idea, or else you learn nothing from their mistakes.