While I don't agree, in general, with with the idea you express that 'Crashes and depressions are the only viable way to rid the world of the long unsustainable debt which prevents economic growth,' because it draws a too broad brush and is too general in my opinion. I do, nevertheless, agree that crashes and depressions may be the ultimate result of "unsustainable debt". In your remarks, there seems to be an implication that the 'world' is on the verge of such a calamity, and that is specifically what I would not agree with. Certainly neither the majority of EU countries nor the U.S. are anywhere near the level of unsustainable debt that would cause such a calamity. We saw an event, such as you speak of, in the case of the Weimar Republic, and so that might be a good example of what can follow in such a circumstance. In that instance, unsustainable debt led to 'ultimate[ly]' to extreme nationalism, a Keynesian economic miracle, and a hideous war.When your computer's operating system is too badly messed up, the only way out is to format the hard drive and install a new one. It's pretty much the same thing here.
Crashes and depressions are the only viable way to rid the world of the long unsustainable debt which prevents economic growth.
Problem is with the information age we're living in. While our grandparents during the Great Depression might have felt largely confused and looking for a salvation by the authorities, the modern-day rulers have compromised themselves beyond belief. So when the SHTF, quite a few of them might quickly end up hanging down from the nearest trees while angry crowds will go on with their armed rampage.
I have lived a long time, and in the course of my life I have learned that I have often been wrong because I was unaware of things I would have had to know in order to be right. Lately, my record has somewhat improved, I must have learned something along the way.