Well, Arum is kind of right.
Economies don't get screwed over by evolution (which I presume he means, business running it's course), economies get screwed by specific isolated incidents - usually orchestrated by a controlling entity, such as a government (which can implement policy level changes) or *significant* holders of capital who, on occasion act in concert intentionally or unintentionally to create change.
One of the first major, MAJOR, arguably, the biggest collossal f*ck up of all time, was when, Nixon, in 1971, decoupled the US dollar from gold, and effectively changed the American dollar from being "gold standard" to a currency.
A currency, by definition, creates value from movement ("current" => "currency") implying, there is no inherent value. Currency by design, only has value in movement. As soon as currency doesn't move, it devalues rapidly (note the biggest problems in recent years being major solvency issues of banks - this is slightly different, but implicitly related: there was no *movement* of currency, and this caused very, very significant problems in many economies around the world).
The decoupling of the US dollar from the gold standard meant that the US treasury could literally print money.
Why would they do this?
There are a lot of reasons. Among the largest are:
* at the time, it meant that the US could borrow a LOT of money from the US treasury which the treasury printed to meet the US governments demand
* because the currency wasn't linked to a held gold amount, the treasury didn't need to acquire gold to print the money
* the increase in currency in circulation (note that "circulation" is another word indicating flow) meant that that there would be an inflation of dollars in the system, leading to future dollars being worth *less* than current dollars... WHICH MEANS:
* that the significant loans the US was taking out from the treasury would devalue, benefiting the loaner
Now, this is only one of the many very significant mistakes the US made. But you can bet that the trumpeter will likely make a few while he's in office, and he's already trying to get the Dodd Frank reform bill repealed which pretty much will throw a massive spanner into the financial system again.
Here's a reasonable summary:
http://www.abc.net.au/news/2017-02-0...ations/8243688