Respectfully, goseyloosey, I disagree.
I think the anti-consumerist 'movement' is driven my various groups of people, but not specifically the older generation. I also think there are many good reasons not to consume in excess (obviously a very subjective term, but anyway...)
Environmental reasons: The more we consume, the more we make plastic, the more coal we use, the more we burn, the more trees we cut down, the more chemicals we use, the more we throw away, the more goes into landfill...etc
Social justice reasons: Much of our consumption is at the expense of workers in developing countries, who's cheap labour enbable us to buy three vests for £1, or whatever.
Closer to home, materialism undermines social values where people are valued for their character, rather that their possessions.
Financially: The more we consume the less we have to spend generously and help others.
Relational reasons: The more we spend, the longer our work hours, the less time we have to devote to relationships.
Greed: The more you have, the more you want, which feeds all of the above.
More controversially (but no less importantly imo): Humans are designed to love and serve God and others, not money, and you can't do both.