That's one good example of why understanding percentages is important as it pertains to money. I'll give another one that has [since the turn of the millennium] hit a lot of ordinary working Americans hard...

Someone who has a retirement account from work will likely have some portion of it (X dollars) vested in the equity markets. Maybe they rode a good wave and saw their X-dollar portfolio increase by 50% before the tech or housing bubble burst and caused their portfolio to lose 50% of its value. Alternatively, they might have experienced the bubble bursting first and thus their portfolio lost 50% of its value, before recovering with a 50% increase to their portfolio's value afterwards. Unfortunately, either way, the end result is the same...

If the rise came before the bubble burst, the person's current portfolio value can be calculated as 1.5X * .5 = 0.75X.
If the bubble burst first and then the recovery occurred afterwards, the person's current portfolio value is represented as 0.5X * 1.5 = 0.75X.
Either way, they're left with 75% of their original stake, a net loss of 25%.

It also makes for a good illustration of why it can be very difficult to recover from losses in the stock market.