The best part about this is you can give most of the credit to their own citizens as the government didn't really do anything aside from letting the crypto industry be legal in their country, the South Korean government didn't really do some kind of promotion but just legalization of businesses related to crypto and that's it. The citizens of Korea are the ones who figured out that Bitcoin and other cryptocurrencies has more room to grow as compared to other assets. Only if other countries gave these kind of friendly laws for the crypto industry I think other nationalities would be more open to a riskier alternative from the stock market.
That's more than enough for many places. South Korea is not a third world nation, they are quite strong in economy compared to many other nations, they have global products that people use all around the world, they are probably second most known mobile phone company in the world as well (samsung) and basically all around a good nation, if some small tiny african nation supported it that may not be a big deal, but when south korea allows it, that is a good news.
Look at USA, they allowed it, but each state had a different tone for it, for example New York "allowed" it but in reality they started to just make it incredibly difficult, so there are few in there while many in other states, long story short we are talking about something that could actually make a big difference depending on how you allow it and where you allow it, which would help it grow a lot.