Yes Ellie, I know nothing about economics. You've got me 
All I have is graduate-level education and many years of experience working in financial markets, both on the sell side and on the buy side. No, I was never an accountant, but some knowledge of accounting is of course essential when working with financial statements.
"people in Greece were buying Mecedes cars because they believed they would not depreciate in value against the backdrop of a depreciating currency."
That's nonsense and I certainly hope you know it. People fecklessly buying Mercedes cars with EU aid money were just doing what feckless people do - spend money unwisely rather than invest it for a rainy day.
"When a currency fails, all other assets hold greater value"
No, They Don't. I'd understand investing in gold coins or some such, but not a car which loses value on the first day you own it.
"there are many cars that do not depreciate in value"
There is no such thing. You are being silly.
"you've made one step, now take a look at who owns those entities?"
I've made one step, have I?
You mean who owns the American investment funds that own Goldman Sachs? Please don't say you don't know what an investment fund is.