To be more precise, FDR increased the price at which the government would buy gold from foreign buyers. The devaluation occurs in terms of foreign currency exch

To be more precise, FDR increased the price at which the government would buy gold from foreign buyers. The devaluation occurs in terms of foreign currency exchange. I don't think it's quite correct to put a 1:1 correspondence to that and "eliminating 50% of the value of everyone's savings". Maybe eliminated 50% the value of everyone's savings in Francs. Domestic purchasing power would be negatively affected for foreign goods, in theory it would create income in terms of increased exports.