If bitcoin ever goes mainstream it will surely ruin the lifes of all the ones invested in fiat (see
https://bitcointalk.org/index.php?topic=180798.0). Gresham's Law will destroy their fiat savings, since everyone will want the stronger bitcoin and will dump fiat, devaluating it. We'll see it happen first in the troubled economies, with high inflation and generalized suspicion on governmental money because of past problems.
The lives of those heavily invested in fiat is already being ruined due to 0% interest rates, negative interest rates in denmark and switzerland and a whole host of other things
A mere 0.5% rate hike in the US will totally obliterate pension funds, life savings and investments held by 90% of the country