Hillary Clinton was a major proponent in the overthrow of Gaddafi.

Libya was actually one of the best-performing countries in Africa under his socialist leadership (perhaps "socialist" isn't a totally correct term; he was... unfriendly to communists and didn't side with the USSR during the Cold War, but in practice there are similarities between his policies and socialist ones), but his anti-imperialist stance and material support for anti-US groups brought sanctions to Libya. This was especially problematic given that the socialist policies that Gaddafi enacted were funded largely by oil, and so sanctions on that oil was a critical weakness. Things deteriorated inside Libya during the 80s/90s but eventually Libya and the West came to an agreement to open things back up. Now in a post-USSR world and concurrent with US wars in the Middle East not far from him, opportunities for supporting anti-imperialist militant groups were rarer, so he focussed more on a grand project of African political and economic unity against American imperialism, such as the creation of an singular African currency which would have been called the "gold dinar", as well as a single African passport and a singular African army. These efforts towards de-dollarization are, in hindsight, among the first rumblings of the dollar's downfall in the period after the 2008/9 financial crash (authors such as Radhika Desai were writing about how this crisis portended a coming multipolarity a full 8 years before the Russia-Ukraine war, when serious discussions of it began).

The Arab Spring was quickly used against him by America, with NATO offering their support to anti-Gaddafi rebels as well as bombing factories. When Gaddafi was murdered, Libya plunged into a civil war that rages to this very day, creating widespread poverty in the chaotic aftermath and, indeed, slavery. While Obama and others in the establishment have expressed some regret over how things turned out, it's clearly not serious enough regret to impact policy, given that the US still loves to spread war and bomb countries that oppose them.

The message here is to adopt a more internationalist stance. Many liberals in the general public are unfamiliar with the atrocious foreign policies that many politicians implicitly or explicitly support. The most monstrous liberals even support those atrocities. If you ignore these policies, one could almost convince themselves that Clinton and others weren't really that bad; sure, a little old-fashioned, a little too capitalist, but the only reason why you could be filled with utter hatred of her is because of a Russian disinformation campaign funded by Trump or whatever. Knowing her history reveals her to be a heartless ghoul up there with Kissinger. Biden has a similar history, but there's even less of an excuse for supporting him, because many of his worst policies were and are domestic and the genocide he is supporting is literally ongoing. And lesser evilism is an unviable strategy; we've been trying it for decades and things have consistently gotten worse. The implicit argument is that we have to endure the lesser evil for now, but at some point the government/president can be pushed left and things will actually start improving rather than just getting worse slower. This point has never arrived despite many years of trying, and people versed in Marxism and leftist theory more generally are completely unsurprised about this, while (usually white) liberals continue to fall for the trap and derangedly claim that you're actually racist if you don't vote for the person who is building walls on the border in a continuation of Trump's policies, boosting police budgets, and bombing countries that are trying to stop the genocide of 2 million Palestinians.