It seems almost silly to get so nitpicky about a topic so broad, complex and variable. Anybody with the vaguest notion of how statistics work knows that... well, somebody could "prove" that cyclists are safer when they wear helmets. Somebody else could use a different set of statistics to "prove" otherwise.

So, statistically, given the studies that have been done and that the members of this forum are using, helmets are both safe and unsafe. Both arguments are "true."

So it comes down to a matter of choice. If you don't think a helmet will make you safer, don't wear one. My instinct when I'm riding is that the helmet that I'm wearing is causing me to be more safe. It's just a feeling. Maybe only marginally more safe - but my gut tells me it's better than nothing.