Did the collapse happen while the life of ordinary Britains improved greatly? Yes.
Did the USSR collapse? Yes. Is the quality of life for the ordinary Russians better today? Yes.
Holy Roman Empire, Greek civilisation, Roman empire: Same story
Maybe today it is better, but that didn't help the millions of Russians who drank themselves to an early grave since the 90s:
http://www.aei.org/publication/russias-demographic-disaster/
> Russia witnessed 6.6 million more deaths in this fifteen-year period than would have occurred if the country had merely sustained the mortality schedules from two decades before.
http://www.nybooks.com/daily/2014/09/02/dying-russians/
> By the mid-1990s, the average St. Petersburg man lived for seven fewer years than he did at the end of the Communist period; in Moscow, the dip was even greater, with death coming nearly eight years sooner.
Sadly, the poor, rural, white parts of America are going through a similar demographic crisis right now, while the rest of the country is busy vilifying them as racists.
Systems collapses have very negative consequences for those who depended on the old system.
When the USSR collapsed, people in the Eastern Bloc didn't stop writing stuff down.
The USSR and British "collapse" were the loss of empires, not a collapse of civilization. The systems of society were shuffled but not destroyed.
It's a perfect example of the fall of an empire and civilization without any collapse.