There's no doubt that TB likes to keep his interests private, but it isn't really a 'rags to riches' story based on gambling. His grandfather Harry (vice chairman in the 70's) was a multi millionaire and I think that the family have always had very well managed diverse interests across the world. TB has simply kept this up very successfully. And simply doesn't even start to cover the complexity involved
Not quite the 'Professional gambler who has made all his money through gambling' that the press always like to portray
It has been reported that he has a massive property portfolio. I think the gambling (and even Starlizard) is mostly a bit of fun. Money making fun, of course, but if you have the skills and ideas, why not?