There was an interview in 2003, in which they say it is their full time job and they had been making the sim for 3 years. That means they started in 2001 or earlier. First they worked practically for free. Then some people started preordering, and when S1 came out in summer 2003, they started to get paid for their work.
During autumn 2004 (when everyone believed S2 was just around the corner, but it wasn't) they made hard pushes trying to release S2 in 2004. Scawen posted several times how much they worked for some periods. Later after S2 alpha came out in june 2005 I believe they slowed down a bit. As for now I think they keep moderate pace, we've seen large improves in patch U.
Back to topic. Almost a year there were between 20,000 and 30,000 racers. Part of them were still S1. It seems patch U and bf1 attracted some buyers, and it could be around 30,000.
During autumn 2004 (when everyone believed S2 was just around the corner, but it wasn't) they made hard pushes trying to release S2 in 2004. Scawen posted several times how much they worked for some periods. Later after S2 alpha came out in june 2005 I believe they slowed down a bit. As for now I think they keep moderate pace, we've seen large improves in patch U.
Back to topic. Almost a year there were between 20,000 and 30,000 racers. Part of them were still S1. It seems patch U and bf1 attracted some buyers, and it could be around 30,000.