I run a moderately popular browser game. We have over 175k registered users and get millions of requests a day.

Our conversion rates are low, but we've managed to get enough people playing to sustain itself, one full time employee (me!) and a few contract employees.

It's been a lot of fun. If you are passionate about games I highly recommend it since it can definitely be sustainable. Having said that, I'm not sure it's necessary a lucrative path for most people.