As long as there are some sellers who are willing to take what the market is willing to pay at any given time, then for most products all I need to do as a buyer is wait for the right one to come along. This breaks down a little when we deal with super-limited quantities, but I've come to accept the fact that I just may never get that xx/10 card I'm looking for.
Sellers who hold these cards out of the market are simply exercising a form of monopoly power - and this is one of the few areas where they can legally do so. However, that doesn't mean it's a smart business practice - we generally have enough substitutes in our collecting preferences that we can avoid those sellers.
I'm mostly a buyer, but when I do sell, it's to actually move the product - not to have it sit there month after month. I set a minimum price that I think might actually get at least one bid and am perfectly happy to get that price. Everything above that is gravy. This keeps everything nice and simple.
Citing a truism like "My card, my price" is ultimately self-defeating if your intent is to convert your cards into cash. If you insist on getting a price that is consistently above the price most people are willing to pay, you are cutting yourself off from your market and are relying on outliers (e.g., desperate collectors who feel compelled to temporarily exceed their normal price constraints in order to get the card). This is grossly inefficient not only for you but for the market as a whole. I don't know why this isn't apparent to those who engage in the practice, but maybe that's why the hobby industry isn't exactly known for its resilient business models. ;-)
Finally: As a buyer, I don't even bother to read further when I see the seller is phoenix1588 or iceinvestor or any of the other highballers out there. I'll try once or twice to get a seller to accept an established market value, but if they refuse then I don't even bother to try *ever* again. This has grown into also not bothering to make an offer even if I don't know if the seller is reasonable or not. This is the hidden cost of starting out with high prices; you may be willing to take a reasonable offer, but those offers might never even come in.
Sorry for the rambling post, but I too am tired of seeing the stupidly high pricing on items month after month - it dampens my enthusiasm for the hobby in general.