Is it possible to interprete (not translate) here "spielt" as "making an object of derision, ridicule, mock" or it means just "playing (football, golf etc.)"?
why does this sentance use the article "den" instead of "die" if Eigentumern is plural?
because it is in dative case.
It uses den because it is dative (plays WITH) plural.
Without any context I'd say the first proposition is more likely hear.