In order to use cryptocurrency to buy a cup of coffee, indeed, this cryptocurrency must have a fast transaction speed, I would say instantaneous. However, this is not one important condition, there are others. Also, this cryptocurrency should be demanded and accepted by the community, as well as by a number of states where it could be used to pay for goods and services. Based on this, I still find it difficult to give an exact answer to this question and will continue to observe the development of crypto indutria.