I'd actually use the 0.13% chance (of an accident injury helped by a helmet in a year) instead of the 0.65% chance because it's more likely to be closer to reality. I'd never wear a helmet if those were my odds, it would be silly.

But those aren't my odds - those are considering the whole population of people who say they ride a bike in a year. Maybe they ride a couple of miles two or three times in the summer, they're included. So it's still silly to say "everyone" should wear a helmet all of the time when there's a tiny chance that it will be useful, because we'd be generalizing to the whole group. Most of what I see in helmet advocacy is misguided in my opinion, for this very reason. Put simply, wearing a helmet is of almost no benefit to the large majority of these people.

I wish helmet advocates would restrict themselves to saying, "for 'this' type of riding (explaining why), accidents are more likely and you should wear one" and acknowledge that "for most casual riding, there is little danger and use your best judgment." There wouldn't be so much pushback from the gross exaggeration of the dangers.

I probably ride ten times or a hundred times as much as the median of that group, in all kinds of weather, and probably a different kind of riding. My individual risk is far greater. For my own risk I look at accidents per mile, or per hour if I can reasonably relate it. I try to weigh in aspects of the specific routes that I take, against the relative frequencies of accidents (intersections, type of road, rural vs urban, time of day, etc), and I judge that against my personal capabilities. We all do that to some degree I think, and call it "judgment". It, the risk, is enough that I don't feel foolish at all wearing a helmet most of the time, nor do I have the slightest qualm about riding bare-headed for a short trip.