Actually most software developers I know are 40+.  Don't know many younger ones because there's been very little hiring in the past 10-15 years.   The Silicon Valley companies, in particular, like to hype their young workforces, but behind the scenes, most of the programmers are in their 40s and 50s, American programmers.  Also if you've ever been to the Silicon Valley, its devoid of nightlife -- exactly what you wouldn't expect of a place filled with youth.