I hear you...I'm pretty much a straight up collector...when I sell stuff, it's either because I've upgraded, or I've decided to no longer collect something...so, I tend to fall more on the "board flipping is annoying" side of things. However, I've seen the debates about this on here before, and I understand both sides of the argument. Also, I've come to understand that it's just part of the current landscape.
I'm one who doesn't understand the problem. Ed, if you bought a book from me say at $50 because I'm liquidating books and in a hurry to get cash, and you realize the book is worth considerably more to the right buyer, why would you feel obligated to resell it for only $50?
There is neither sin in seeking profit nor is there any exclusive right of "dealers" to buy cheap and sell dear. Its a free market for everyone. That is the beauty of it, and that it is a free market likely contributes to the volume and variety of books available for you to collect.
The issue has always been with people trying to get a deal in any way and then resell here at a higher price, effectively rubbing the original sellers nose in it. And the debate is very old, I have never cared for in forum flips, I have always seen them as poor form. For awhile some of us even entertained how long should there be posession before flipping on the boards. But again, I never cared for it, and try to avoid dealing with those who do this.