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I was going to say that nobody makes money distributing GPL software for $$, however I proved myself wrong with my own software.
https://play.google.com/store/apps/details?id=com.metalrain.stocksimulator.android
I published that a few weeks ago, GPL on GitHub and $1 in the market, and I just checked today and I've made almost $10!!!
Given how long I spent on it, it may in fact pay for itself in it's life span, and I might actually do some updates.
However, there is nothing stopping someone else from making a fork and distributing it for free, and if it get's popular enough that'll likely happen pretty quick.