It's called 'disinhibition' and it's been seen many times before... Previously with the HIV epidemic: "oh there's treatments now, I don't have to wear a condom."

At a certain point some people, faced with a challenge they can't see, will somehow just assume it's no longer really there, despite all the evidence to the contrary. It's a massive liability.

This isn't a supernatural force.. it has parameters and if everyone did the right thing at the outset (seal borders, 3-4 weeks of real self isolation), then the lion's share of this could've been avoided.