If you live in a country with poverty, bad government and a poorly functioning welfare, religion looks like a respectable source of hope.
The means by which JWs validate their presence in the world is by numbers of believers. The more people persuaded by the org to join them, the stronger the case for their existence.
It would be interesting to uncover the motives of those baptized who are drawn from a culture which is not generally critical of religious sects. Most faiths are acceptable because for the majority of Africans, it is socially demanded to be a believer in God hence religion is still a way of life.