Only if you take an extremely tautalogical definition of "worth" of limited usefulness. If you strengthen it even a little bit further, towards a definition tha

Only if you take an extremely tautalogical definition of "worth" of limited usefulness. If you strengthen it even a little bit further, towards a definition that takes into account a degree of repeatability, then a single transaction is not sufficient to establish worth. That also accords better with general English usage, where what something is worth and what a particular person paid are not considered generally equivalent. There exist phenomena such as "overpaying" and "getting a great deal", where payment in a particular instance diverges (in either direction) from this more robust notion of "worth". Indeed, if that were not the case, arbitrage would be impossible.