Why would anyone support the Sith, AKA the "Betraying Space Wizards party?" Doesn't that sound like a surefire way of getting a dagger to the back? Yet support for the Sith and other fascist governments who betray their supporters is so common that the term ‘Leopards Eating Faces Party’ was coined to describe the bizarre behavior of people supporting groups and institutions who turn around and eat them. Just look at Dedra, Syril, and Dooku.
All three served the Empire or Palpatine, and all three are rewarded by being devoured, just as they devoured others. The storyline is satisfying. These villains don’t even get the limelight from a traditional death at the hands of the hero.
Dooku’s death was but another gear turning in the machine of the Empire. Syril is unceremoniously shot after being unrecognized by his sworn foe. Dedra is locked away. All three are consumed by the very awfulness they created and perpetuated. They experienced what they subjugated others to. While the bitter machine of the Empire continues, their endings show exactly what happens to those who work for fascist governments.
Why did any of them choose to serve the Empire? Dooku had all the experience and wisdom attributed to a Jedi Master, Dedra had intimate experience with the harm her chosen institution wrought, and Syril wouldn't need five minutes of research to find out about the Empire’s cruelty and horrors. They all actively took part in the worst the Empire has to offer, is it no great leap of logic to think ‘If the Empire can do this to someone else, can they do it to me?’
Debra, Dooku, and Syril all had the information and forewarning they needed to know their own fates. They all had moments of realization, moments where they could have turned away from all the evil they had done and escaped betrayal, torture, and death. None of them did.
For Syril, it was easier to hate a brown man for 'losing him his job' than to hate the Empire for betraying his supposed ideals of Justice and Order. Dooku would rather double down on the dark side by murdering Yaddle than face the reality that he was working with the man who orchestrated his Padawan's death. Dedra would rather cling to the power the Empire allots her than challenge a system that inherently sees her as lesser.
They all thought they were exceptions to the Empire's rule of betrayal and eating faces. Fascist groups are good at convincing people that there is a line between 'you' and 'them'. They are equally good at convincing 'you' that someone's face deserves to be eaten, that for the good of society/your self-interest, someone's face needs to be eaten. This reassures supporters that, of course, their face will never be eaten because they are not one of 'them.'
The Empire successfully convinced (almost) everyone that their genocide of the Jedi was not a foreshadowing of other genocides to come. Besides, the Jedi had to go. They were child thieves, they were war mongers, it was they who started the fight. The Republic cheered for genocide, but there was no difference, to the Empire, between the Jedi genocide and the Ghorman genocide.
...sounding familiar?
No fascist regime eats ‘your’ face; they do keep that promise. The problem for people like Dooku, Dedra, and Syril, and for everyone who believes ‘their’ faces must be eaten? We are all capable of being a ‘they’ to a fascist institution.