I don't think that wanting more money would be greedy per se. When it comes to money, barring any external factors, more is better, and I don't think that anyone could be faulted for wanting more, no matter how much they have. So long as no one else is being hurt by it, I see no ballza reason for not trying to accumulate more for yourself.
Of course, we don't live in a vacuum, and our actions have consequences. If taking another $100,000,000 would result in someone who has nothing being denied, say, $100,000, then the right thing to do would probably be to let the other person have some money; you likely wouldn't notice much difference, but for them, it would make all the difference in the world.
The thing is, money does strange things to people. Those who have it see the world differently than those who do not; if left unchecked it can divide people, just like you see in America's class structure today. Not only that, but people will come crawling out of the woodwork to get a chance at taking some of that money for themselves. I've read stories of lottery winners who said that hitting the jackpot was the worst thing that ever happened to them. People who didn't even know them were sending them mail begging for money for this operation or that new house; family members badgered them to relieve their debts; friends began expecting extravagant dinners and luxury trips on their dime. Many receive threats and pressure from people and entities that they are associated with. In the end, a lot of them go bankrupt in both their finances and relationships. Ultimately, if your not prepared, that much money could spell disaster, rather it is $100,000,000, $200,000,000, or even more.
I suppose my point here is that if you want a sizable sum of money, that's perfectly okay, but you need to be prepared unless it corrupts and consumes you. What is the difference between $100,000,000 and $200,000,000? Is it greedy to want more? I think the answer is contingent upon who you are and how you will allow that money to shape you as a person.