OMG guys quit bitching. Helmets are definitely at least helpful. They may not protect you from all injuries, but they will often protect you from dying. Look at schumacher for example; he would have almost certainly died instantly without one. So if you wanna accept that you can die: good for you, get eliminated from the gene pool.
And to Putissiman: Pros get injured, and worse, killed. Whether you like it or not. There are many examples of this, and the main problem isn't THEM, because although they do much more dangerous stuff, they know their limits. It is the people they inspire that are the problem, along with the trends they set. Although, the helmet could save your life. Even if there is a 5% smaller chance of dying, wouldn't you take it??!
TL;DR wear a helmet, don't be a bitch.