An interesting suggestion

The Lack of Major Wars May Be Hurting Economic Growth - NYTimes.com

Tyler Cowen writes:

Counterintuitive though it may sound, the greater peacefulness of the
world may make the attainment of higher rates of economic growth less
urgent and thus less likely. This view does not claim that fighting wars
improves economies, as of course the actual conflict brings death and
destruction. The claim is also distinct from the Keynesian argument that
preparing for war lifts government spending and puts people to work.
Rather, the very possibility of war focuses the attention of governments
on getting some basic decisions right — whether investing in science or
simply liberalizing the economy. Such focus ends up improving a
nation’s longer-run prospects.

Here's the last few paragraphs:

There is a more optimistic read to all this than may first appear. Arguably
the contemporary world is trading some growth in material living
standards for peace — a relative paucity of war deaths and injuries,
even with a kind of associated laziness.

We can prefer higher rates of economic growth and progress, even while
recognizing that recent G.D.P. figures do not adequately measure all of
the gains we have been enjoying. In addition to more peace, we also have
a cleaner environment (along most but not all dimensions), more leisure
time and a higher degree of social tolerance for minorities and
formerly persecuted groups. Our more peaceful and — yes — more
slacker-oriented world is in fact better than our economic measures
acknowledge.

Living in a largely peaceful world with 2 percent G.D.P. growth has some big advantages that you don’t get with 4 percent growth and many more war
deaths. Economic stasis may not feel very impressive, but it’s something
our ancestors never quite managed to pull off. The real questions are
whether we can do any better, and whether the recent prevalence of peace
is a mere temporary bubble just waiting to be burst.

 Spotting a large, alien spaceship in the outer parts of the solar system, heading towards Earth, may give a good replacement sense of purpose.