Re: vested interest in supporting the value of the currency
The expected lifetime of a fiat (ie, issued by government and not backed by anything) currency is about 30 years. You'd be surprised how many national currencies have failed within our lifetimes.
See http://georgewashington2.blogspot.co.uk/2011/08/average-life-expectancy-for-fiat.html. "Twenty percent failed through hyperinflation, 21% were destroyed by war, 12% destroyed by independence, 24% were monetarily reformed, and 23% are still in circulation approaching one of the other outcomes."