Greed

Here is a definition of Greed from wikipedia:
Greed is called a selfish desire to obtain money, wealth, material possessions or any other entity than one legitimately needs. Greed is listed as one of the Catholic seven deadly sins, usually by the synonym of avarice.

I've always been so offended of greedy people. Greed is like a poison and can ruin relationships and tear families apart. Bob experienced greed when he had a business partner, it ruined the business relationship and friendship between 2 people.

Why are some people willing to compromise friendship, family, relationships over money?