Capitalists don't use their greed for good, they use it for profit. The more their products and services benefit their (greedy) customers, the more profit they have.
Discussion
And if you're denying that we're greedy, you're just pushing that trait into the "undesirable" bin, a personal shadow, from which it comes back in subversive, sinister ways.
Greed (avarice, covetousness, excessive desire for goods or power, or love of money) is always bad. It breaks one of the Ten Commandments.
http://www.scborromeo.org/ccc/para/2536.htm
Someone who cannot engage in capitalistic endeavors without falling into greed, should abstain, to avoid the occasion to sin.