Billionaire insurance mogul and property developer Douw Steyn has died.Steyn, who had been in poor health for years, was 72 years old.He leaves behind sons TJ and Louis and widow Carolyn Steyn, a music radio presenter and founder of the non-profit organisation 67 Blankets for Mandela.Giuseppe Plumari from Steyn City Properties, who made the announcement about his passing, said: “Douw will always be remembered as an exceptional entrepreneur who built a global business of immense scale across seven countries, and a visionary with a deep-seated commitment to South Africa and its…