Well, there's also the size nuance here -- that you need to spend far less than you'll end up earning. For the non-Chinese speakers out there, it literally means "Spend [a] small [amount of] money, make big money," with the same implication found in the techie epigram "Weeks of coding can save you hours of planning."

It roughly correlates to the expression, 'It takes a little bit of money to make a lot of money' -- implying the need to spend a little and also the contrast in relative quantities.