Has anyone ever taken the risk of voting against incumbent North Korean officials?
Has anyone even voted in reality ?
Yes, in many dictatorships it's dangerous not to vote, particularly if you're pursuing certain particular professions. My grandparents were regular CPSU voters once upon a time. Of course the North Koreans come out and "vote" for the regime.
What's the point of Dictators giving people fake ballots to cast in fake ballot boxes when they can just make up the whole thing anyway ?
Just have the Dictator go on TV and announce an election took place which they won, without all that useless paperwork.
To have the populace universally vote is taken to be a sign of strength for the regime and becomes propaganda. It's also used as a kind of census, to track the number of defectors since the last election.