A series of large cryptocurrency scams is rocking Uganda, turning the East African nation into an unlikely hub for fraudulent firms claiming to offer digital currencies, while preying on weak governance and low financial literacy. Globally, cybercriminals stole $4.3 billion from users and exchanges last year. But Uganda is the worst hit — by far. At least five cryptocurrency firms have closed shop and walked away with a total of more than $26 million of their clients’ money in the past six months. From students and churchgoers to army officers and government officials, the victims span Ugandan society. Robert Bakalikwira, a criminal investigations officer probing these cases, estimates that in all, 200,000 Ugandans have lost about $1 billion, or almost 4 percent of the country’s GDP of $28 billion, over the past two years. The country’s growing crisis holds lessons for other poor nations with weak regulations unable to keep up with the sometimes misleading promise of technology.