Not cryptocurrencies but Blockchain and its general applications that should be added in student's syllabus. We all know that crypto is just one part of the technology. Teaching them crypto investment at this stage is like teaching them how to gamble on this highly speculative market.
I think that blockchain needs to be taught as a subject but as a part of an already existing subject because I feel like it's not going to do any good if we make it a subject since it's not in everyone's interest and @Obito is right, it should be a specialization.
The objective is general awareness so it doesn't really matter to me if it can a stand alone subject or a sub. It can be taught under Economics since blockchain and its benefits will be a huge part of the economy of each country. Specialized courses can be offered to those who want to pursue careers from the technology.