People look for purpose outside of themselves. Increasingly, in secular societies, there is nothing outside of themselves.
On a local forum up here recently, a poster, commenting about a local Christian organization that is serving the homeless, wrote, "Well, if evangelizing about some guy in the sky is what it takes, so be it." He, of course, ignores the question, "Why does it seem that most or nearly all of the organizations that have any durability over time are the Christian ones, while the secular ones tend to fade away over short periods of time?" Not to get too Biblical on you, but one is built on stone, while the other is built on sand. Talk to non-religious folks about something approximating purpose in life. In modern times, that boils down to two criteria:
1. Something that makes me feel good. Emotions.
or
2. Some explanation of a moral purpose that is obviously rooted in some Judeo-Christian ethics, but completely unrecognized or unacknowledged as to its roots. As such, the purpose itself may be fleeting or pass with changing winds, hostage to whichever ethic is currently fashionable in popular culture.
Hardly the makings of a contented existence.