Japanese software company Optim's 43-year-old Founder Shunji Sugaya, who turned down an offer from SoftBank to buy his idea for $2.8 million at the age of 23, is set to become a billionaire. Optim's shares gained 79% this year after rising 7.9% on Wednesday. Sugaya's net worth, derived mainly from his 64% Optim stake, has surged to $990 million.