Sharky:
In large part, I beliece the Kondratiev Cycle reflects that as we progress with time and generational progression, the lessons of the past recede, allowing for repetition of economic mistakes. For example, the generation which experienced the Depression of the 1930's is now substantively gone and with them the experience of that time. So, we have basically had four generations since the last economic calamity. This is evidenced by observation of the reckless economic and fiscal follies.
As generations progress and then die off, we then consequently see a repetiton of the cycles as the populace no longer has cognitive recognition of the dangers surrounding their excessively risky behavior. Indeed, they likely do not even recognize their behavior as risky. Thus the stage becomes set for calamity!
Brian