Maybe it is as a result of our population because with the population count we have, we should be dominant in anything that we have most of our people focused on and I think for cryptocurrency this is the case This is why I can understand and believe the 60% estimation among other African countries considering we have a large population of youths with many interested in crypto and more coming in. Nigeria will dominate those figures for a long time.
Lists of 3 most populous countries in sub-sahara Africa:
Nigeria: ~242.4 million people
Ethiopia: ~138.9 million people
Democratic Republic of the Congo (DRC): ~116.5 million people
Can you see that just the population of Ethiopia and DRC is more than our population if both are added together.
The total population of Sub-Saharan African people is approximately 1.3 billion people. That is more than 4 times larger than Nigeria population if Nigeria is excluded from the 1.3 billion people.