well , don't we all invest our most valuable asset - time into earning money and other , less important stuff  ( like actually living )
affiliate marketers at least are earning money through others , saving time eventually
like  John D. Rockefeller  once said : "I would rather earn 1% off a 100 people's efforts than 100% of my own efforts."  - can't be more true for affiliate marketers , the successful ones
because too many of them are only investing time and often money to get no profit because they didn't estimate the profit potential of an offer
 or spent too much money on a low return ad etc. , it is not an easy job and more often than not you lose out
and of course , the psychology of a billionaire is not "I earn 1 billion and then call it quits and buy an island and drink and have sex on a beach till the end of my life"
once you get the taste of big money , there is no stopping , its a dangerous game ... I wish to participate in one day