Its possible for a nation to overestimate their military might. Look at some of the US's embarrassing wars when they were forced into Guerrilla warfare. But there are still limits. There is no way russia thinks they can beat Nato in a conventional war. Its why their strategy is around developing technologies that maintain nuclear effectiveness (though I think anyone looking at the numbers has to have some serious doubt about how nuclear capable russia really is).
There is no way russia thinks they can beat Nato in a conventional war.
That is exactly what they think. Same with north Korea etc. Propaganda and disinformation are powerful tools to manipulate people.