I think a lot of people are underestimating, the amoralness and ideological flexibility of most people in high ranking leadership roles. If the person who holds the keys to power and promotions and tells them to believe X, most ambitious feds, most ambitious military officers will immediately and publicly espouse that they always believed X. When the pendulum swings back, well...then they will espouse that they always believed Y. As long as power and wealth can be aqcuired by espousing leftist politics, then the powers that be will be full throated supporters.
In essence what a lot of these people say and do in public is not their true face, their true beliefs. But a mask they wear to signal compliance with the regime, to show that they are trustworthy. Behind closed doors I guarantee that these people are probably just as nasty, grasping and hateful as every one else. Probably more so, because to behave that falsely requires an overwhelming amount of psychopathic behavior.
The leadership is pro-left, quite a few people in the federal government are actually right wingers just doing a job.
The reason the leadership is pro-left though is because lefties want a massive centralized federal government to deal with every issue the country has, while the right wants strong local powers to deal with issues unique to their locality.
Basically this. They support current leftism for several opportunistic reasons :
1) They're pro technocracy and centralised nanny government, and current leftists are compatible with this because they reject private property and individual responsibility
2) They're pro-globohomo, like liberals, but for different reasons. Immigration has been a way to bring down wages, and break strikes, for centuries. I don't think the US establishment is as much pro immigration as the EU tho. Anyway, promoting diversity in the workplace reduces unionizing and revolts against the hierarchy. Globohomo, in its globalization meaning, is also a way for the US to spread its soft and smart power around the world. It's a double edged sword for them.
3) Liberals, except some tranny anarchsits, are strongly against all means for the common citizens to arm themselves. They can scream "ACAB" all they want, by removing the right for the citizens to arm themselves, they leave the monopoly of legitimate violence to the state.
4) By breaking gender norms with LGBTQ+, they're pushing men to spend a lot of money on beauty and fashion products, as much as women. They don't want women to reject beauty standards either, in order to keep their existing consumer market. This is why liberal feminism pushed by the establishement is pro sex and "pro bimbo", and call radfems that reject female sexualization nazis.
This is why leftism in its original socialist form became marginal. The establishement promptly understood the need of the youth to feel rebellious, which politically translated to the left (at least after WW2), and they repackaged it in a form that suited their plans. I think this shit can be traced as far away as the 60's, and leftist movements became more and more eaten away from the inside.
Basically they're useful idiots.