Offering well below asking price/lowballing isn't by itself being a choosing beggar, this person is just negotiating, seemed to be perfectly reasonable, and willing to take no for an answer. Plus, this person didn't even realize it was an original peice, making their offer totally understandable. CBing is demanding a ridiculously low/ no price for an item, guilt tripping a seller with their kids/alledged sickness, believing oneself is entitled to an item for little to no cost, expecting the seller to bend over backwards for their every desire, and refusing to take no for an answer.

TL;DR- trying to negotiate a cost doesn't make someone a choosing beggar, believing you're entitled to whatever you want for little/no cost, and throwing a fit/guilt tripping a seller when told no does.