The cost of a thing is the amount of life that you must exchange for it -- now or in the long run (Thoreau)

• if you have an on-going relationship -- even as limited as a note payable -- squeezing the last nickel out of the deal may impair your bargaining partner's ability to perform 
• what goes up, must come down, i.e., squeezing out the last nickel creates enemies who  none of us can afford when times are good, let alone when times are bad 
• taking advantage of another's weaknesses tears at the social fabric
• it makes us all more watchful and less productive
• it doesn't actually feel good to line your pockets with the misery of others
• sometimes the downtrodden rise up -- every couple of centuries or so, creating an entirely new order -- the generous man and woman will not be on the wrong side of that revolution
• global warming -- think about it -- the order will change as will the countries who will be asking for favors
• you reap what you sow (I'm pretty sure I learned this in Sunday School)
• social relations do not exist "out there" -- they are co-created by one person's relationship with every other person -- the society you inhabit is the one you create -- if you don't want your neighbor taking your last dime, don't take his
• collaborative effort results in greater progress than individual activity -- if you decrease trust, you impede advancement in business, the arts and science

Readers!  Can I count on you to give us all more reasons?