Was not the Swiss Franc about $3 back then? There were no Euros to compare but that would seem quite a hit.
Very true of many coins. Generally, the drop of the Iron Curtain in Eastern Europe and the rise of metal detector finds also kept prices lower during the mid1980s-1990s, at least for types that could be found there or were held there until markets opened-up.
I think you may have the rate reversed. According to the following table from Wikipedia, the historic exchange rate in 1970 for the Swiss franc was 4.373 Swiss francs to the dollar: So 8000 Swiss francs in 1972 was about $1,800 (I think this was before foreign exchange rates were allowed to float). Adjusting for inflation, $1,800 in 1972 is about $10,000 today so this coin's value has not held up well no matter how you calculate it.
I think many people look at coins primarily as an investment. I agree that this is a fundamental mistake. As with any area of collecting, interest and passion should be the guiding principles, of course, within one's financial means.