why do sellers change asking price to sold after a sale?

[Fred]

Perhaps in some cases, the seller doesn't want to disclose the sale price because there are those the saw the "offer to sale" price and will be able to gauge how much a seller will negotiate the next time something is offered for sale.

I'm not afraid to send an offer to a seller. Worst case is that they say no or there's further negotiation. What's poor form is when people just completely low ball the seller, or (and I know I'm going to get an earful about this next comment) is when someone has a really nice sale price and someone buys it to flip it quick to make a few bucks. In my opinion, if someone has a nice price on it, let it go to another board member that can appreciate the card and hold on to it because they truly want it as part of their collection - ok, bring it on, let's hear the reasoning about capitalism and "if one person didn't do it, then someone else would do it".