why big strong empires fall to zero

empires are like hurricanes, which are srengthened by hot air wipe evrything in its way becomes strong and then peters out, on a dfferent time scale. end is inevitable for many reasons. 

in case of empires there are many reasons

resources of young motivated to grow people dwindle.they become complascent and stagnated.material resources start getting exhausted slowly without any alternative and people get perplexed. malaise sets in on the empire with increase of drug use. education standards fall. in fighting becomes fierce and power centric with ulterior motive.no strong leaders to pull the empire out of fall. people have limited choice of petty leaders involved in their own agenda.

just look for these signs in your nation where ever you are ...