How Is General Zaroff Able To Finance His Life Style?

Zaroff seems to like living on an island, hunting people all day and all night. In any case he does mention how he made his fortune,

"After the debacle in Russia I left the country, for it was imprudent for an officer of the Czar to stay there. Many noble Russians lost everything. I, luckily, had invested heavily in American securities, so I shall never have to open a tearoom in Monte Carlo or drive a taxi in Paris."

Zaroff came from nobility and invested his money in American securities. Now he lives on an island with a guy who can't talk (Ivan)!