from wikipedia: "The tragedy of the commons describes a situation in economic science when individual users, who have open access to a resource unhampered by shared social structures or formal rules that govern access and use, act independently according to their own self-interest and, contrary to the common good of all users, cause depletion of the resource through their uncoordinated action."
when people opt to sell

for astronomical prices for their own gain, in turn inflating the prices of

, that's tragedy of the commons.
when users of Gaia sell items for astronomical amounts of gold, leading to a Greece-like situation, that's tragedy of the commons.
they could continue buying and selling like before lava lamps or whatever Gaia did, but they won't cause it would take the entire community maintaining that with nobody doing self-gain. people would buy

on kofk and resell them for much higher prices.