An desire to survive. The more you have the better chance you have to survive.
This is the coolest, most simple and perfectly correct answer I've read in a long time. (And no,... I'm not under the influence of any substance.)
I'm not sure but we'd still be living primitive if we didn't have that desire.
A government that always does it's best to see we have less.
Greed and a need to impress others