1. I got into bikes at college. I could ride somewhere in 10 minutes that took 30 minutes to walk.

2. I bought a decent mountain bike.

3. I bought a nice mountain bike. Actually took it off road.

4. Ran into a single speed mtb somewhere online. Liked the idea. Converted an old frame.

5. Saw messenger bikes around town. Puzzled at their brakelessness.

6. Stumbled into this forum, looking for a couple answers about SS parts. Found that nobody gave a **** about mountain bikes here, only fixed road bikes. Figured out #5.

7. Got tired of riding my 32x16 mtb around town. Bought a nice old road bike.

8. Got tired of maintaining / worrying about theft of the road bike.

9. Utilized a couple of the 20+ frames in my basement to build a fix. Worked great. New challenge. Fun. Promise of finding people to ride with.

and so on...