Overplaying increases the baseline of perceived risk, so you'll have to overplay it even more next time to provoke the same reaction. That's difficult, because once you're at "we're all going to die with 99.9% certainty", will people really care tomorrow when it's 99.99% or 99.999% the day after that?

It feels a bit like throwing antibiotics at everything. Sure, it's effective in the moment, but you're lowering the future effectiveness.