The older you get, the trickier money gets between friends. As some of our pals excel in the money-making department, others fall behind. Sometimes it's because they're woefully irresponsible - they buy drugs with their pay, or drink and gamble it away. Other times it's because they have focused on less lucrative job opportunities. Many of my friends, for example, consider themselves musicians first and workers second. And while they create incredible art and feel gratified by the hours they sp…