two problems here:
1) we don't know surbitcoin website, and it is hard to trust a site that is unknown with lots of money. also it seems like they have some problems (https://news.bitcoin.com/surbitcoin-shut-down-bitcoin-crackdown/)
2) this type of arbitrage trading needs access to banks over there in Venezuela to be able to withdraw the money which is impossible for us in other countries. and there is always risk of our accounts being banned because of it.
there is also this:
https://bitcointalksearch.org/topic/m.15508607
apparently people can not even take their money out! (a bit old news but still it is a problem)
