It's for internal consumption. The average life quality is dropping both in Russia and the West, so the governments need to divert attention and redirect the frustration to external targets. The "NATO being a threat to the whole world" is the Russian version of "Climate Change will kill us all, so don't even think of starting a family (and wondering why your current salary makes it rather challenging)".

NATO bombed Yugoslavia in 1999 without UN authorization under the pretext of "humanitarian intervention". See https://en.wikipedia.org/wiki/NATO_bombing_of_Yugoslavia

NATO is a sticky situation with the Russians. The one thing the Russians fear more than anything else is encirclement, so any organization of potentially hostile nations is immediately looked upon with suspicion.

Also, they're still sore that some negotiators in 1990 promised more on NATO than the USA was willing to deliver. This is oft-repeated in the upper circles of the Kremlin, and regardless of its validity it's still a strong sentiment.

NATO is a threat because NATO is enemy. there is kind of circular logic over there.

Russia has always in been conflict with Western powers, and has been invaded on several occasions.

You mean like bombing Libya?