Many (though certainly not all) Orthodox Jews fit the bill as "crunchy cons." Most of their money goes toward educating their children or spending for the Sabbath & holidays. Although materialism has encroached on their society as well, many manage to live quite modestly.
I believe, anyway, that conservatism breeds modesty. It's the nature of the beast. Someone who is traditional in his values & lifestyle seems to lead a more simple life. Consumerism is tied in with ego -- the need to draw attention to oneself. The more one's attention is turned toward G-d, the less self-centered, period. And the more incentive to want to pass on values to children -- as well as have children. Liberals by their very nature have fewer children, or none at all.
There is a lot of truth in your short message. I happen to be a Christian but I'm afraid that I like nice things and sometimes I can get caught up in it all. It's not really an ego thing, it's more, I think, because I truly love beautiful art, music, and so on. I notice it and so I can't stand things when they are "uglified." So, for example, if the carpet gets bad, I want new carpet. I can't help it. However, one nice thing about beauty is simplicity has its own beauty and one can have beautiful things without spending a lot of $. Anyway, I do design work so I guess it's just an innate part of me.