whether the cause of this is happening, is it something to do with the decision of the south korea government?
The market's value is always depending on the supply and demand of every cryptocurrency that is listed. Another thing is that, altcoins prices is based on bitcoins so it was normal for other alts to decrease its value in the market, the best thing to do is read different positive speculations and news to boost your confidence if you are worried about the downfall of prices.