Probably because I'm not going to get all upset over an
offer that isn't "high enough". It's always bugged me how
people are insulted to the point of complaining. Weren't you
ever new to the hobby? Haven't you made uneducated offers
before? If someone offers you something that isn't near the
price you paid, or the current market price or whatever -
then be polite and brush it off.
If they really want it, they will (do their research and) offer
higher. In the meantime mind-reading won't work and you'll
have to be patient while they decide how much they want to
offer. If it's not up for offers anyway, then just say so. No
need to be insulted.