French economist Thomas Piketty has written a book, Capital in the Twenty-First Century[amazon template=f_textamazon&asin=067443000X], that discusses a very simple fact of snowball effect economics: as long as r > g, that is wealth generated by capital is greater than economic growth, capital will tend to accrue with a select few.
Piketty holds an interesting TED talk about the snowball effect in economics.
So what does this mean for game designers? Simple: as long as passive income earns you more points than active income (i.e. actions) your best bet is to invest in money, nothing more.
For example, take a look at Fresco. There you’ve got multiple types of actions, from buying paints, to mixing paints, to keeping your workers happy. But if you play without any expansions then all those actions are worth too little points in comparison to the simple action of taking money all the time (the so called “Big Money” strategy). Unmodified Fresco has a r > g strategy: don’t grow, just take money.
Add in a couple of expansions and suddenly the other options become much more viable as you get higher returns on your other actions.
So keep an eye out for your r > g situations and you’ll be able to avoid snowball effects.