Why do people (generally) become so angry and defensive towards accusations of materialism?

When you accuse someone of being materialistic, they become defensive right away, most of the time anyway. Yes I agree it is all about the money. Look at the Presidential election going on right now. You hear so much about who has the most money. Is that how we are to decide how we vote for our next president, things are in a sad state, instead of helping our fellow man, we are in general all out for ourselves. Now that I have said that I live in N. San Diego Ca. where all the fires have been burning, and the outpouring of kindness has been amazing. So with that thought in mind. I don't think all is loss, human kind does come together during a disaster, and I pray we can be like this a lot more often.