Who remembers Hetfield's "I am the table"?
Somewhat similarly, I could state I am the source

To explain: so I develop some drivers and tools for Boot Camp, and counting just two primary download mirrors these have been downloaded millions of times by unique users. Yet it's safe to assume much bigger group of Boot Camp users may not even know about them, because I never truly advertized anything. For example: I don't run any banners, ever. I don't even have any YouTube video on this topic, and neither related social network accounts. But people anyway find and download the drivers. To me personally this situation is an indirect (but still reliable) proof how big the real Boot Camp users community is. As for the daily usage: I have long-term and daily email feedback from people where it's almost always mentioned they use their Boot Camp daily (and really need it).