It's probably going to be a loss for them because those who may wish to do business with cryptocurrencies, or think of starting a startup or something that involves cryptocurrencies, they will probably move to a country that allows them to do that without any problems, such as the UAE, which is very friendly when it comes to crypto and people from other countries moving there to run their businesses because they know it's going to grow their economy because of the money they can generate from these businesses, and it will also grow their technological infrastructure as well in the long run.

Greece or any other country doing this are going to regret it in the long run, because they are basically trying to suppress the technology and stop its growth, but they don't understand that the technology won't stop by doing this, but this is only going to cost their economy a boost that they could get if they were a bit more generous towards it if their people are actually interested in it.

Governments are mostly selfish, they barely think about the well-being of the country or the people, all they do is directly or indirectly to empower themselves.