On yr 2nd pt, that seems plausible, though I’d say that it’s more about novelty than virtue (naturally the two categories overlap a lot in this modern world) … basically it’s fear of the unknown. It takes quite a long time for a new thing, and all its implications, to become known and understood. After a generation or so, the risks of whatever-it-is become internalised, factored in, discounted. After that, it’s not something people worry about, unless something happens to suggest otherwise (eg something like September 11 could have happened decades earlier, but very few people in Western countries thought of aeroplanes as particularly risky objects anymore). That has holes big enough to fly a 767 through but it’ll do for a blog comment.

Thought - each civilisation worries about a doom that has a lot to do with its virtues, not a doom that’s actually likely. ‘Tanks on the lawn’ is still the best way to take down an advanced country, but the public mind will persist in looking around them at their state’s virtues, and seeing how these could be turned into threats. Commerce. Airlines. Teh interwebs. Etc.