I'll leave it to the viewer to decide what constitutes "active" and "manage." I manage 3 different BI sites (home, work, and my parents' house), and in total there are 65 cameras. I think that's a little nuts, but I'm already planning for several more, because more is better, right?
I suppose I could have written "how many cameras do you have running?" as opposed to "how many cameras do you own?" because I'm sure we all have dozens of cameras either in the junk drawer, the workbench, or the "someday" inventory box.
I have 9 at my place, 4 at a client's home about 25 miles away and 3 at a business (a combo freight broker and tanning salon ) about 11 miles away; all locations 3 run Blue Iris.
I remotely manage BlueIris and 16 cams for my Sister 10 hrs away. I also manage Blue Iris and 5 cams for my daughter 8 hrs away.
Plus my own 13 cams. I don't have to actively "manage" any of them, they are setup properly and they simply do their job.
The problem with this poll is that it will automatically and inevitably skew towards the higher counts: those with modest numbers will tend not participate at all (fear of being mocked as a n00b, nothing worth bragging about, etc...).
It won't really represent a random sample of this forum (which will, in itself, skew much higher than the general population for number of cameras "managed").