The global economy is nearly 80 trillion USD per year. Payments using any type of cryptocurrency as a medium of payment is a tiny fraction of this total.
What are some of the reasons preventing cryptocurrency from being more successful as a medium of payment?
It is actually the start of the cryptocurrencies that is why you are seeing like this and even in the start you can see that how much faster the process of adoption is going. The cryptocurrency itself is being used as asset too by the traders which make the price of it fluctuating which also made the process a little slower but that is not a hurdle it will spread all over the world as payment sooner.