I would like to add there are generally four causes/reasons for someone to betray their country:
M - Money - self explanatory
A - Anger - "you don't respect me, passed me over for promotion, ignored me, so I'll show you"
L - Love/Lust - "oh baby, you're so great in bed, I'll do anything to be with you"
I - Ideology - ie "Communism is better and I support it"
C - Coercion - "you have a very pretty daughter - hope nothing bad happens to her"
E - Ego "I'm the smartest person in the room"