I'm kind of the same way, though like Rolf I recently restructured my knives and have settled on two (I think) that will keep me happy for a long time.
OP, do you have a good knife shop near you? I don't, and sometimes I think that it's just a matter of needing to hold and experience a knife. I think I'd spend a lot less time online and that I'd order a lot less knives if I could run over to the shop and handle a bunch.
As others have said, I wouldn't worry about it. I think that part of the hobby is trying out/checking out new designs, features, brands, etc. If you can then turn around and give another enthusiast a good price or gift a knife to someone, then all the better! I recently let got of a ZT 0566 for cheap, but it made the guy really happy. I also just gifted a Lon Humphrey to a friend of mine who was floored by it. If I'm not using a knife, making someone happy always seems better than keeping it in the drawer...