Those are the people who Yuri Bezmenov was referring to when he spoke of ''useful idiots'' (useful to the Soviet Union and still to Russia today) who can be presented with all the facts imaginable, but they will never believe in the brutality of Gulags (and the Soviet regime in general) until they end up there themselves.

the longest sentence was 10 years

25 years. But you could go to a Gulag as many times as the authorities wanted, for whatever reason.

The aim was to correct and change the ways of criminals.”

Funny they call them criminals, considering that most of the imprisoned had not commited any real crimes, but were either political opponents, people who refused to collaborate, intelligentsia, people who had more property than was acceptable, entire families of the previous four groups etc. Just pretty regular people, many (perhaps most) of whom were imprisioned without ever being brought to a court.