Wht the hell happened to them? Why did they collapse so easily?

AO jaan,

Because deep down, 14 centuries of brainwashing and nonsensical "teachings" has done so much damage that our culture has never recovered and never will. Even some of the seemingly progressive Iranians still beleive in the "hazrat-e this and that" and "dast-e borideh abolfazl" and crap like that.

Most of the masses put religion ahead of nation and that, my friend, is the problem.

Add to all this the relentless pursuit of leftist ideology and dissimination by the Soviets immediately following the 2nd world war and during the cold war that resulted in the formation of Tudeh "party" and leftist/socialist groups that helped the islmist pukes - and we get the large stinking pile of shit called the essslamic regime you see today!

Well Now that you Jomhurykhah EYE RANIANS in the Diaspora successfuly turned Reza Shah Dovom into "Shahrvand" Reza the TV Presentator ... 

I doubt there is the slightest chance of restoring that past Glory you now seem to regret ...