How did the past nobles and royal families earn their living?
I'm a big fan of watching movies with old English settings, such as literature adaptation films (Pride and Prejudice, Jane Eyre, etc), even Sherlock Holmes and Wolfman (2010).
I'm always fascinated with the life of the nobles depicted in those movies; living in a huge mansion, dining with formal attire on, surrounded by full time servants who live within the compound (such as in Brideshead or Downton Abbey). So from where I see in them, they seem to live a life of eternal financial security.
I was wondering, how did (or do) the nobles earn their living?
As far as I know, they have land that they lease it to the peasants/farmer surrounding their territory. But is that all?
I imagine if the nobles and royals are still widely prevalent in current time, most of them would be listed in Forbes 400 of richest individuals or something.