[quickthrower2]

Rather than Lazy/Work hard it might be more speculate/save. In a bull market you are trying to throw more money in. In a bear you are trying to save. It is self reinforcing too.

[DoreenMichele]

That's reasonable, but it's still substantially about human behavior not some abstract algorithm that can be inferred. That's my main point.

There's no certain number of years or something that causes it. It's human behavior and real world limits, like Peak Oil.