In Argentina, a new tax is about to be approved that will charge profits for holding cryptocurrencies with 15% per year. (
Source) This tax applies for everybody that made profits of more than approximately 3.500 USD per year, so everybody that held more than 0,25 BTC in 2017 would be affected.
This tax will be possible to be charged retroactively, but it will come into effect on January 1, 2018. So everybody that sells before that date, will not have to pay the tax for profits that have accumulated until that day.
Even if you don't believe it: Argentines are a significant Bitcoin holder group. A history of restrictive exchange regulations (the last "restrictive" phase lasting from 2011 to 2014/2015) made many people aware of cryptocurrencies. And at least one of the historical Core contributors is an Argentine.
So it's a pretty likely scenario that Argentine holders could move the price a bit. But maybe it's nothing to worry about: They could re-buy at January 1, so they get only charged for profits after that date.
Is it bad? Absolutely. And they seem to be targeting explicitly cryptocurrency holders, it seems. It doesn't apply to gold or other assets, just cryptocurrencies. And 15% is a pretty high amount to pay, especially if you're just a small time trader barely making the 3.5k cutoff mark.
But it's not going to crash bitcoin, 100% no. If bitcoin crashes by the end of the year it's not because of this new rule in Argentina.
They may obviously hold some bitcoin as a nation but they are nothing compared to korea/china/japan/usa, etc. And when china banned exchanges the markets reacted with nothing. I doubt they'll be reacting any worse for this case.