Hot take: capitol citizens are not evil (with the exception of snow and the game makers, mostly)
I don’t think the average Capitol citizen was inherently bad or evil. they’d been propagandized from their early childhood that the hunger games were ethical and that district people were less than human. take Hitler Youth for example, they’d been surrounded by propaganda from a young age, and while once they became adults it was their responsibility to unlearn that, undoing years of damage and influence is difficult (honestly I don’t know what became of former Hitler youth, I don’t know if they ever unlearned anything). also the capitol adults were surrounded by that propaganda into adulthood, imagine how hard it would be to have “hunger games good” ingrained into your brain from birth, and throughout your life, and then to unlearn it. so yeah effie, caeser, and others were cogs in the machine that honestly didn’t know better, and didn’t know anything different. (with the occasional outlier like Tigris and Plutarch of course)