I have about 25 fully live and about 90 total... I am letting the other ones expire as I got them when I didn't have a clue why, just thought it would be nice to own something online until i realized the potential of cpa, affiliate marketing adsense. Speaking of which I think I might just put adsense on them, i was going to park them but soon realized that these parking companies are getting payouts and using googel adsense as well.
So you can imagine why they own over 100,000 domains and then have them parked with cpa, affiliate offers, adsense and chitika ads and even pop ads like clicksor. Imagine you just get one visit for each one of those sites that is 100,000 visits and let's say you get 5 visits or 10 or 20...and out of that you get 100,000 clicks at .5 cent clicks that is 5000 dollars...each day...now you see that domainers are getting smarter even more by creating adnetworks and then doing it from there to build up their networks.