Ask Lemmygrad

There was a general culture of normalization of excessive violence due to the 2 world wars and one civil war they just had to endure plus the lasting legacy of the brutality of the Tsardom.

Stalin himself though, the characterization of him as being paranoid is false, people usually point to the doctors plot as evidence of this but if you read into what Stalin actually did and said during this, he kept throwing doubt on the investigation due to a lack of evidence, he was actually a moderating voice - not paranoid.