It's the same reason we're targeted in the first place and the same reason we were the first target of the Nazis, back then. When things are in decline, people look for someone to blame, and minorities, who are few in number and already seen negatively, make for the easiest target, even if it the furthest thing from the truth. The alternative is to blame the rich, who have the most power to propagandize and shut down that narrative, but the advantage is that it's actually true, which is enough to give it a fighting chance. But what democrats have been trying to say is not that the rich are the reason people are suffering, but that people are not suffering at all. When those are the only two narratives, people are bound to turn to the one that acknowledges their problem, even if it's full of ridiculous lies, it's a doomed strategy.

As for the democrats turning on us, at the risk of reigniting a debate, it's because of trolley problem logic. If a minority group like Palestinians can be sacrificed for the sake of winning an election, then the same can and will be done for any minority group that becomes seen as an electoral liability. The only way for any minority, but especially one as small as trans people, to really achieve security is through solidarity, an alliance of the vulnerable that treats an offense against one as an offense against all. Right now, there might be cis gays watching the democrats blame trans people and thinking that they'll be safe, but that's not guaranteed at all. Since we've been on opposite sides of the debate, I expect you will still disagree with me, but perhaps you can understand where my side's been coming from.

For many people living in safe states (like myself), their vote will not affect the outcome of the election. However, whatever choice is made there (including staying home) will define your political identity and influence your thoughts and actions. Millions of people just voted with the idea, "It's acceptable to sacrifice a minority group in order to win, because it can prevent a worse outcome," and in doing so, they allowed that idea into their minds and allowed their hearts to become more callous. The only surprising thing is that they'd announce their turning on us so soon, when there's not even an election coming up.