http://airfactsjournal.com/2012/10/mayday-the-declining-pilot-population/

It is no secret that there are fewer and fewer active general aviation pilots
every year. Why is that true? Can we arrest the decline? Will the activity ever
grow again?

The factors most commonly cited when discussing the decline are money and time.
Those are excuses, though, not factors. Flying has always been expensive and
learning how to use an airplane has always taken a lot of time.

One reason there are fewer pilots is because the mood in our country has
changed. There is more of a tendency today for people to be needy and dependent
and risk-averse. That is not a good demographic for flight training or for
flying.

Thanks to Fred Wilson