> or did you also just not have expenses as high as your original estimate?

The market went up much faster than I originally estimated. Basically, I got lucky.

I quit my job in 2009, right when the massive bull market started. I had a bunch of stocks and mutual funds that I planned to sell in order to support myself.

Which I did: What happened was that my stocks and mutual funds appreciated faster than I spent them. (If I hadn't sold them, they would have doubled or tripled in value over the 18 month period.)

For example: The day after the iPad came out, I sold my Apple stock at a nice profit to pay my expenses for a month.

Ironically, if I had stayed at work as long as I planned, I probably would have had even more runway. (But then I wouldn't have landed the awesome job that I got when I went back to a salaried job in 2011.)