I was reading a piece about John Mackie who was present at Wepener. The article said:
Sunday in the trenches is described in the Sunday Strand by Mr. John Mackie, who has been through eight battles and survived the siege of Wepener. He says that gambling is the curse of the army in Africa. Low-class Americans joined the Army merely to rake in the pay of their comrades. Several took their discharges with over a thousand pounds apiece in their pockets as a result of their gambling exploits. “The greatest gambler of all was a most inveterate coward.” When he had amassed £1,200, he tried to buy off taking his place in the firing line.
I hadn't noticed many mentions of gambling in the literature. Creswicke makes some disparaging remarks about Johannesburg being "a sink hole of abomination equal to Chigaco" (Vol 6, p202) but other than that, very few mentions and certainly not a documented curse.