There are several such Billionaires who stay away from flaunting their wealth & like to stay obscure. There are Billionaires like James Simons, Robert Mercer,

There are several such Billionaires who stay away from flaunting their wealth & like to stay obscure. There are Billionaires like James Simons, Robert Mercer, Azim Premji etc. who steadfastly keep a low profile; whether it is humility or if it fits their agenda is a topic for another discussion. If we count the number of Billionaire names we remember, I'm sure we wouldn't even cover the top 25; so I don't think the list matters for anything significant except for the Income Tax departments of their respective countries.