Please remember that for a serious recreational cyclist, the correct answer to "how many bikes should I own" is:
From my experience in the local road racing scene, a majority of the 200 or so cyclists that participate in the weekly training racing have at least four different bikes. I suspect that the percentage that only owns one bike is very, very small.
fwiw i race bikes and commute and i only currently own 1 bike. The rest get handed down or parted out. I also own 4 cars at the moment. These stats are irrelevant though because they were all purchased used--which i think is the biggest flaw with this study.