Mint started out as not profitable in any way, and I believe at their IPO (which was ~18 months later) they had an ARPU of something like 35-40$ per annum.
You need to reach a critical mass in users before you can take action on certain potential profit centers. It's different for every industry and every business, but there's some things that would be more trouble than they're worth at 25k users but start making you a lot of money at 100k users.