if you think about it you can maybe make big money.
some countries because of war they have big inflation so if you buy today their money there could be 2 option or after the war is over this money will be worth a lot more then you have pay or the country will change his currency and you lose everything.
for example iraq, syria, and countries in africa. i know people that bought millions of iraq dinar (cost few $) but one day the money could be worth a lot!!!
think about it, it is worth to invest on it about 100$ ... (=119043.37 iraq dinar) in 1973 1 Dinar = US$3.3778
if this will be back then you will make from 100$ = 401174 $
This an economic fenomenon called Galloping inflation, the problem is that the currency devaluates in relation of other foreign currencies (goods becomes scarce and costly) . the currency in fact never recovers its value.
To afront these situations government offers higher value bills, of course no body wants it but as a souvernirs as stated above.