The spartans of ancient greece had the Agoge, where the males would leave their families from the age of 7 to train to become the future generation of soldiers.
The agoge is considered harsh as a soldier training regime that I doubt any 7 year old would volunteer for without some
brainwashing persuasion (they were given a limited amount of food so they would be used to hunger on the battlefield, encouraged to sneak and steal but punished with beatings if you are caught stealing, encouraged to fight each other to prove their strength) but those that survived would be "exceptionally trained". Failing the Agoge (and somehow making it out alive) would mean the person could not become a citizen of Sparta.
It was part of their culture, and not done to enslave the people that took part (though they were not paid) but more to make them stronger members of their society for the greater good of all.
In the end it comes down to a question of belief and perspective. If a person believes that serving in the First Order is the right thing to do
as they have been brainwashed then it is an honour for them to be working towards the goal of galactic peace, by defending themselves and those under the protection of the Order from the violence of the Rebellion.
The perspective of star wars is always shown as "rebels = good, empire = bad" and the empire has
a nasty habit of blowing up the occasional planet an aggressive population pacification policy that means the audience then sympathizes with the one man who swaps side because then he CHOOSES to kill people, instead of being TOLD who poses a threat and should be killed pacified for the good of the empire.
In one possible future where Disney decides to reboot the entire star wars series from the point of view that "empire = good, rebels = bad", someone will be on here asking about the unruly teenager who was bad at doing his chores, didn't listen to his family, handled stolen imperial property, became proficient in "bulls-eyeing" rats from an aircraft, ran away from home, joined a rebel army and committed terrorism by blowing up military installations.
Has he been radicalized by the old fugitive with mind control powers he met in the desert, or has he always been a bad guy?