The reactionary fedora tipping type of atheist is a phenomenon limited mostly to the United States in my experience, and it seems to be in reaction to the particularly odious form of evangelical Christianity which exists in much of the States (particularly the Bible Belt). In Europe, Christianity is much more civil, and (probably as a consequence) so too are most atheists. Religion is very rarely brought up in conversation here, and it's generally considered rude to proselytize.
I don't think most people here really "become" atheists. I think it's more born of an indifference to religion as a concept, and an incredulity towards the objectivity of religious claims. Speaking for myself, there was never a point where I "became" an atheist; I've pretty much always been one, and there was never any social pressure for me to believe one way or another because like most people where I grew up, my parents are really just nominal Christians.