Thars like saying "the reason the best employees are good is that they are paid the most money". You're putting the cart ahead of the horse here.
They are dedicated partially because they can spend their time focused on doing their job and not grinding leet code looking for the next pay bump in 2 years. Those pay scales are very strict in government, and very predictable.
And you think the reason they are dedicated is because they mostly care about having a "stable job"?