An answer at Quora:
Simple way? People are weird. We can exploit that.
Slightly less simple way. Human psychology has some known twists in it. We’re really pretty good at working out the costs and benefits of something out to 15 to 20 years ahead. We’re not so good at 40 years out. This is known as “hyperbolic discounting”.
There’s good reason for it for us humans. Through the process of evolution very few adults then lived more than another 20 to 30 years.…See More