Your friend seems to be arguing that both the greater good of society and your own personal well-being would be better served if neither you nor anyone else rode bicycles on the roads. While superficially well-formed, it is a argument based on an assumption about an unestablished statistic. I mistrust any argument based on either of those things--one based on both is, shall we say, weak?

I would argue exactly the opposite, in fact. If anyone should be put off the roads, it should be your friend and his/her automobile. This argument is supported by the health benefits to the riders, the reduction of ca$h flowing into the coffers of the many corporations that profit from an oil-based infrastructure, the harm to the environment caused by motor vehicle use on a large scale, and the crazy foreign policies our oil-dependent lifestyles bring about.

A lot of times we believe what we believe because it is convenient, not because it actually makes sense.