The thing about free to play games with in app purchase is that there are a few "whales" who spend so much money they dominated all revenue statistics. Here's a video from Kongregate talking about this phenomenon on their platform (which has since broadened to include android games):
But the middle aged women demo does not think like your typical HN reader. And that demo is orders of magntude larger than the HN community.
At best, OP should pray to monetize 2% of their audience. Of that, only maybe 15% end up being repeat customers.
and remember, 37% of all stats quoted on the internet are made up. but you get my point ;)