How much is enough?

How much is enough? If one has three houses is that enough or would he/she need two, five, or eight more to have enough? What about shoes, if one has seven pairs of shoes would that be enough or does one need one more to have enough, would they need thirty more to have enough? Is enough determined by the ability to get it in the closet, garage, room, etc.? What about money, if one has eighteen million, should that be enough, what if they felt they needed 100 million more to have enough? Where one might be content with two vehicles and that is enough for him/her, if another feels he/she should have five more vehicles to have enough, is that OK, excessive, greedy, etc.? Where or in what way does not having enough become greedy?