Brexit is a bad example because the predictions were accurate. If you are a foreign investor (your main currency being something other than GBP) and invested in the FTSE then the loss on your GBP was higher than your profit on the index. Slightly different story for UK based investors: While you made a profit on your FTSE ETF, those gains will to some extent be offset by a rise in inflation. Stocks are in general a good protection against higher inflation - which is exactly what is happening in the UK.