Because they want to forget

It’s different for different people. At the end of the day, all the status quo needs to continue is a lack of effective organized resistance, not full support.

That said, from some anecdotal experience: Some of them just don’t care. Politics comes up with my parents a lot. They’re Democrats, but if you talk to them long enough, you realize they’re just functionally Republicans who are embarrassed by the aesthetics of the GOP. The problems they’ve had with people like Trump or Bush have essentially nothing to do with their awful policies and more to do with them looking stupid. They pretty much unquestionably support US imperialism and are depressingly Zionist. Sometimes this seems like it’s down to a lack of historical knowledge, but honestly if you push them on it enough you eventually break out of the loop of America always being the good guy to just a basic “might makes right” and “it’s us vs them” mentality which you’d normally associate with conservatives.

For example, when I’ve spoken to my Dad about Iran, his position ultimately boiled down to “They’re the bad guys. Trump should be attacking them, he’s just doing it in a stupid way that isn’t working.” The fact that the US isn’t merely not waging an effective war, but actively committing war crimes like bombing schools? Unimportant. The fact that we only have the current Iranian government because of previous US meddling? “That was so long ago.” The fact that the last time they were told a country we were targeting had WMDs, it was a lie? Doesn’t even register. When he said someone should do something about them having nukes, I asked if someone should do something about the US since we have the most nukes and he said something like “I’d like to see them try.” The fact that we are currently allied with a literal monarchy in the region? /shrug. When the conversation drifted briefly to Vietnam, he said that either we shouldn’t have gotten involved or we should have done even more. We just didn’t try hard enough to win… There are still children being born in Vietnam with birth defects due to agent orange. But yeah, we totally didn’t inflict enough violence on them.

To the extent that either of them does take an interest in history, it is almost solely through the lens of documentaries glazing the “great men” of our history while ignoring or downplaying their atrocities.

I think my analysis of their kind of politics is that they have enough shame to maintain their ignorance in order to have cover for supporting the things they actually want. You push that ignorance hard enough and the “freedom and democracy” mask slips off to reveal what amounts to little more than support for white supremacy and fascism as long as it doesn’t affect them or make them look bad.

I’m sure there are others that are simply ignorant and could be convinced with enough evidence. I suppose I was one of them. How could I not be? I grew up with the propaganda version of American history where we were the good guys, except for the times when we weren’t, but those are in the past and we’re better now. It wasn’t until near the end of HS that I started getting a more nuanced view of history and once I understood that my politics weren’t actually aligned with my values, I changed. But even then, the effects of the propaganda are so strong that even today, knowing what I know, I just don’t get the visceral reaction to these past atrocities that they deserve. I know they’re wrong, I just am so removed from them that it’s hard to fully empathize beyond a conscious, intellectual level.

There may be more types, but those are my primary experiences. People who are either currently misinformed or people who actively delude themselves so they don’t look like or believe themselves to be similar to the vulgar hicks they view the Republicans as.

EDIT: I also always want to caution against equating the voters with the people at large. The vast majority of the country doesn’t vote. Only some of that is apathetic people. A lot of people are pushed out by deliberate voter suppression tactics. I’d wager that those voters are way more likely to be anti-imperialists, but they don’t get represented by the ballots and media.

The US didn’t just magically turn out this way because everyone wanted it. From the very founding of the country, the system of government that was set up was explicitly designed to limit the influence of popular opinion. You’ve definitely learned about this in school, but it was probably framed to you in terms of “Not letting a majority oppress a minority” without explaining that the “minorities” the founders wanted to protect were white, protestant, land owning men who then turned around and oppressed all the real minorities.

Because government does things that large populaces can’t or won’t do for themselves. Sometimes that’s things like Social Security, regulating companies so they don’t enslave us or dump DDT all over the place, or organizing enough coordinated violence to prevent other, more aggressive governments from coming in and taking over. Sometimes, usually when the people aren’t paying enough attention, it’s horrible things like building Gitmo or supporting Israel.

Ideally, everyone would be well-informed and engaged enough to immediately hold government accountable when it does horrible things in our names, but for a lot of people life is hard, and they’ve been actively discouraged from having that education and engagement, usually by one flavor or another of psychopath who wants to get away with their atrocities and not be answerable to a decently informed and engaged electorate.

Democrats do, on balance, care more about their leaders committing atrocities than Republicans do, but the phenomenon of “I just can’t think about that right now, I’ve got other things going on” is a universal experience.

It’s right to be outraged by this complacency, and I don’t even think anyone is wrong for wanting to disengage from any political party or even politics as a whole in response, but wanting to remain morally pure and wanting to achieve anything of merit within the system we currently have are mutually exclusive goals.

If someone finds politics as a whole, and all of the moral compromises involved, so abhorrent that they don’t want to engage at all, I get it, but they’d really better start looking up how to engage in violent resistance, because change either comes through politics and all of its attendant compromises or through violence, there’s no third alternative.

Because for the most part, Americans are bloodthirsty morons.

US has two party system. You either vote for the seemingly conservative corporate puppet war criminal in camp A, or vote for the seemingly liberal corporate puppet war criminal in camp B.

The most obnoxious Democrat supporters have their whole ego caught up in being a “good person” by having the correct ideological positions. Admitting that their “team” is full of war criminals would directly challenge their egos and is thus summarily dismissed. They are idealists, and thus disconnected from material reality. They tend to be quite caught up in the notion of “electability” - the idea that they shouldn’t back candidates or platforms they actually want, but those calculated to appeal to the largest number, which is always smack dab in the center of the Overton window, in their estimation. (Of course, ironically, a true socialist platform would have the greatest appeal were not USians so propagandized against it.) I have literally had liberals tell me that though they are not themselves racist, they need a candidate that would be accepted by racists. I think more often than not, they cry “electability” so they have an excuse for supporting a conservative candidate while simultaneously calling themselves “progressive”.

This is to say nothing of the fact that liberalism is a conservative ideology, and that it is more than happy to back imperialism if it means the spoils can subsidize their lifestyle. Or in other words, Democrats will cheer for any war if it keeps their Starbucks cheap and their gas tank filled. They are not anti-war at all. They oppose the appearance of warmongering, but not the actions themselves; they want plausible deniability so they can go back to brunch.

Tl;dr - Democrats are bad people who pretend to be good people and back war criminals because they like imperialism, no matter what excuses they make for it.

I mean it’s the same thing when you confront Republicans about it. Both parties have supporters who just want to support that party, and any logic against that gets them in defense mode

Money > Ethics. Its pretty simple, everyone has a price. People will ignore or downplay the shitty things if you keep a certain level of contentment.

Dems don’t care who the leader is. What matters if they’re advancing the agenda. Same reason Republicans cheer on a pedophile rapist.